Add framework for AVR

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2961 42af7a65-404d-4744-a932-0658087f49c3

37 files changed, 4404 insertions, 0 deletions

diff --git a/nuttx/arch/avr/include/arch.h b/nuttx/arch/avr/include/arch.h
new file mode 100644
index 000000000..389e5689a
--- /dev/null
+++ b/nuttx/arch/avr/include/arch.h
@@ -0,0 +1,82 @@
+/****************************************************************************
+ * arch/avr/include/arch.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through nuttx/arch.h
+ */
+
+#ifndef __ARCH_AVR_INCLUDE_ARCH_H
+#define __ARCH_AVR_INCLUDE_ARCH_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ARCH_AVR_INCLUDE_ARCH_H */
+
diff --git a/nuttx/arch/avr/include/at91uc3/irq.h b/nuttx/arch/avr/include/at91uc3/irq.h
new file mode 100755
index 000000000..395c88188
--- /dev/null
+++ b/nuttx/arch/avr/include/at91uc3/irq.h
@@ -0,0 +1,92 @@
+/****************************************************************************
+ * arch/avr/include/at91uc3/irq.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through nuttx/irq.h
+ */
+
+#ifndef __ARCH_AVR_INCLUDE_AT91UC3_IRQ_H
+#define __ARCH_AVR_INCLUDE_AT91UC3_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#  include <stdint.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+ 
+/* IRQ numbers */
+
+/* Total number of IRQ numbers */
+
+#define NR_IRQS
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+#endif
+
+#endif /* __ARCH_AVR_INCLUDE_AT91UC3_IRQ_H */
+
diff --git a/nuttx/arch/avr/include/avr32/irq.h b/nuttx/arch/avr/include/avr32/irq.h
new file mode 100644
index 000000000..cc8222e86
--- /dev/null
+++ b/nuttx/arch/avr/include/avr32/irq.h
@@ -0,0 +1,123 @@
+/****************************************************************************
+ * arch/avr/include/avr32/irq.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather, only indirectly
+ * through nuttx/irq.h
+ */
+
+#ifndef __ARCH_AVR_INCLUDE_AVR32_IRQ_H
+#define __ARCH_AVR_INCLUDE_AVR32_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/irq.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Indices the register state save array */
+
+#defin XCPTCONTEXT_REGS 1
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* This struct defines the way the registers are stored. */
+
+#ifndef __ASSEMBLY__
+struct xcptcontext
+{
+  /* The following function pointer is non-zero if there
+   * are pending signals to be processed.
+   */
+
+#ifndef CONFIG_DISABLE_SIGNALS
+  void *sigdeliver; /* Actual type is sig_deliver_t */
+#endif
+
+  /* Register save area */
+
+  uint32_t regs[XCPTCONTEXT_REGS];
+};
+#endif
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* Save the current interrupt enable state & disable IRQs */
+
+static inline irqstate_t irqsave(void)
+{
+  return 0;
+}
+
+/* Restore saved IRQ & FIQ state */
+
+static inline void irqrestore(irqstate_t flags)
+{
+}
+#endif /* __ASSEMBLY__ */
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+#endif
+
+#endif /* __ARCH_AVR_INCLUDE_AVR32_IRQ_H */
+
diff --git a/nuttx/arch/avr/include/irq.h b/nuttx/arch/avr/include/irq.h
new file mode 100644
index 000000000..8f5ef73bc
--- /dev/null
+++ b/nuttx/arch/avr/include/irq.h
@@ -0,0 +1,100 @@
+/****************************************************************************
+ * arch/avr/include/irq.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather, only indirectly
+ * through nuttx/irq.h
+ */
+
+#ifndef __ARCH_AVR_INCLUDE_IRQ_H
+#define __ARCH_AVR_INCLUDE_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/* Include NuttX-specific IRQ definitions */
+
+#include <nuttx/irq.h>
+
+/* Include chip-specific IRQ definitions (including IRQ numbers) */
+
+#include <arch/chip/irq.h>
+
+/* Include AVR architecture-specific IRQ definitions (including register
+ * save structure and irqsave()/irqrestore() macros
+ */
+
+#ifdef CONFIG_ARCH_AVR32
+# include <arch/avr32/irq.h>
+#else
+# include <arch/avr/irq.h>
+#endif
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+#endif
+
+#endif /* __ARCH_AVR_INCLUDE_IRQ_H */
+
diff --git a/nuttx/arch/avr/include/limits.h b/nuttx/arch/avr/include/limits.h
new file mode 100644
index 000000000..80413e9c9
--- /dev/null
+++ b/nuttx/arch/avr/include/limits.h
@@ -0,0 +1,82 @@
+/****************************************************************************
+ * arch/avr/include/limits.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_AVR_INCLUDE_LIMITS_H
+#define __ARCH_AVR_INCLUDE_LIMITS_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+#define CHAR_BIT    8
+#define SCHAR_MIN   0x80
+#define SCHAR_MAX   0x7f
+#define UCHAR_MAX   0xff
+
+/* These could be different on machines where char is unsigned */
+
+#define CHAR_MIN    SCHAR_MIN
+#define CHAR_MAX    SCHAR_MAX
+
+#define SHRT_MIN    0x8000
+#define SHRT_MAX    0x7fff
+#define USHRT_MAX   0xffff
+
+#define INT_MIN     0x80000000
+#define INT_MAX     0x7fffffff
+#define UINT_MAX    0xffffffff
+
+/* These change on 32-bit and 64-bit platforms */
+
+#define LONG_MAX    0x80000000
+#define LONG_MIN    0x7fffffff
+#define ULONG_MAX   0xffffffff
+
+#define LLONG_MAX   0x8000000000000000
+#define LLONG_MIN   0x7fffffffffffffff
+#define ULLONG_MAX  0xffffffffffffffff
+
+/* A pointer is 4 bytes */
+
+#define PTR_MIN     0x80000000
+#define PTR_MAX     0x7fffffff
+#define UPTR_MAX    0xffffffff
+
+#endif /* __ARCH_AVR_INCLUDE_LIMITS_H */
+
diff --git a/nuttx/arch/avr/include/types.h b/nuttx/arch/avr/include/types.h
new file mode 100644
index 000000000..fd8c394c4
--- /dev/null
+++ b/nuttx/arch/avr/include/types.h
@@ -0,0 +1,95 @@
+/****************************************************************************
+ * arch/avr/include/types.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather, only indirectly
+ * through stdint.h
+ */
+
+#ifndef __ARCH_AVR_INCLUDE_TYPES_H
+#define __ARCH_AVR_INCLUDE_TYPES_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Type Declarations
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* These are the sizes of the standard integer types.  NOTE that these type
+ * names have a leading underscore character.  This file will be included
+ * (indirectly) by include/stdint.h and typedef'ed to the final name without
+ * the underscore character.  This roundabout way of doings things allows
+ * the stdint.h to be removed from the include/ directory in the event that
+ * the user prefers to use the definitions provided by their toolchain header
+ * files
+ */
+
+typedef char               _int8_t;
+typedef unsigned char      _uint8_t;
+
+typedef short              _int16_t;
+typedef unsigned short     _uint16_t;
+
+typedef int                _int32_t;
+typedef unsigned int       _uint32_t;
+
+typedef long long          _int64_t;
+typedef unsigned long long _uint64_t;
+#define __INT64_DEFINED
+
+/* A pointer is 4 bytes */
+
+typedef int                _intptr_t;
+typedef unsigned int       _uintptr_t;
+
+/* This is the size of the interrupt state save returned by irqsave(). */
+
+typedef unsigned int irqstate_t;
+
+#endif /* __ASSEMBLY__ */
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#endif /* __ARCH_AVR_INCLUDE_TYPES_H */
+
diff --git a/nuttx/arch/avr/src/Makefile b/nuttx/arch/avr/src/Makefile
new file mode 100644
index 000000000..a35ed59af
--- /dev/null
+++ b/nuttx/arch/avr/src/Makefile
@@ -0,0 +1,144 @@
+############################################################################
+# arch/avr/src/Makefile
+#
+#   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+-include $(TOPDIR)/Make.defs
+-include chip/Make.defs
+
+ARCH_SRCDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src
+ifeq ($(CONFIG_ARCH_AVR32),y)
+ARCH_SUBDIR	= avr32
+endif
+
+ifeq ($(WINTOOL),y)
+  NUTTX		= "${shell cygpath -w $(TOPDIR)/nuttx}"
+  CFLAGS	+= -I "${shell cygpath -w $(ARCH_SRCDIR)/chip}" \
+  		   -I "${shell cygpath -w $(ARCH_SRCDIR)/common}" \
+		   -I "${shell cygpath -w $(ARCH_SRCDIR)/$(ARCH_SUBDIR)}" \
+		   -I "${shell cygpath -w $(TOPDIR)/sched}"
+else
+  NUTTX		= $(TOPDIR)/nuttx
+  CFLAGS	+= -I$(ARCH_SRCDIR)/chip -I$(ARCH_SRCDIR)/common \
+		   -I$(ARCH_SRCDIR)/$(ARCH_SUBDIR) -I$(TOPDIR)/sched
+endif
+
+HEAD_AOBJ	= $(HEAD_ASRC:.S=$(OBJEXT))
+
+ASRCS		= $(CHIP_ASRCS) $(CMN_ASRCS)
+AOBJS		= $(ASRCS:.S=$(OBJEXT))
+
+CSRCS		= $(CHIP_CSRCS) $(CMN_CSRCS)
+COBJS		= $(CSRCS:.c=$(OBJEXT))
+
+SRCS		= $(ASRCS) $(CSRCS)
+OBJS		= $(AOBJS) $(COBJS)
+
+LDFLAGS		= $(ARCHSCRIPT)
+EXTRA_LIBS	=
+
+LINKLIBS	=
+ifeq ($(WINTOOL),y)
+  LIBPATHS	= ${shell for path in $(LINKLIBS); do dir=`dirname $(TOPDIR)/$$path`;echo "-L\"`cygpath -w $$dir`\"";done}
+  LIBPATHS	+= -L"${shell cygpath -w $(BOARDDIR)}"
+else
+  LIBPATHS	= $(addprefix -L$(TOPDIR)/,$(dir $(LINKLIBS)))
+  LIBPATHS	+= -L"$(BOARDDIR)"
+endif
+LDLIBS		= $(patsubst lib%,-l%,$(basename $(notdir $(LINKLIBS))))
+
+BOARDDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src/board
+
+LIBGCC		= "${shell $(CC) -print-libgcc-file-name}"
+
+VPATH		= chip:common:$(ARCH_SUBDIR)
+
+all: $(HEAD_OBJ) libarch$(LIBEXT)
+
+$(AOBJS) $(HEAD_AOBJ): %$(OBJEXT): %.S
+	$(call ASSEMBLE, $<, $@)
+
+$(COBJS): %$(OBJEXT): %.c
+	$(call COMPILE, $<, $@)
+
+libarch$(LIBEXT): $(OBJS)
+	@( for obj in $(OBJS) ; do \
+		$(call ARCHIVE, $@, $${obj}); \
+	done ; )
+
+board/libboard$(LIBEXT):
+	@$(MAKE) -C board TOPDIR="$(TOPDIR)" libboard$(LIBEXT)
+
+nuttx: $(HEAD_AOBJ) board/libboard$(LIBEXT)
+	@echo "LD: nuttx"
+	@$(LD) --entry=__start $(LDFLAGS) $(LIBPATHS) -o $(NUTTX)$(EXEEXT) $(HEAD_AOBJ) $(EXTRA_OBJS) \
+		--start-group $(LDLIBS) -lboard --end-group $(EXTRA_LIBS) $(LIBGCC)
+ifeq ($(CONFIG_BOOT_RUNFROMFLASH),y)
+	@export flashloc=`$(OBJDUMP) --all-headers $(NUTTX)$(EXEEXT) | grep _eronly | cut -d' ' -f1`;  \
+	$(OBJCOPY) $(OBJCOPYARGS) --adjust-section-vma=.data=0x$$flashloc $(NUTTX)$(EXEEXT) $(NUTTX).flashimage
+	@mv $(NUTTX).flashimage $(NUTTX)$(EXEEXT)
+endif
+	@$(NM) $(NUTTX)$(EXEEXT) | \
+	grep -v '\(compiled\)\|\(\$(OBJEXT)$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | \
+	sort > $(TOPDIR)/System.map
+	@export vflashstart=`$(OBJDUMP) --all-headers $(NUTTX)$(EXEEXT) | grep _vflashstart | cut -d' ' -f1`;  \
+	if [ ! -z "$$vflashstart" ]; then \
+		$(OBJCOPY) $(OBJCOPYARGS) --adjust-section-vma=.vector=0x$$vflashstart $(NUTTX)$(EXEEXT) $(NUTTX).flashimage; \
+		mv $(NUTTX).flashimage $(NUTTX)$(EXEEXT); \
+	fi
+
+.depend: Makefile chip/Make.defs $(SRCS)
+	@if [ -e board/Makefile ]; then \
+		$(MAKE) -C board TOPDIR="$(TOPDIR)" depend ; \
+	fi
+	@$(MKDEP) --dep-path chip --dep-path common --dep-path $(ARCH_SUBDIR) \
+	 $(CC) -- $(CFLAGS) -- $(SRCS) >Make.dep
+	@touch $@
+
+depend: .depend
+
+clean:
+	@if [ -e board/Makefile ]; then \
+		$(MAKE) -C board TOPDIR="$(TOPDIR)" clean ; \
+	fi
+	@rm -f libarch$(LIBEXT) *~ .*.swp
+	$(call CLEAN)
+
+distclean: clean
+	@if [ -e board/Makefile ]; then \
+		$(MAKE) -C board TOPDIR="$(TOPDIR)" distclean ; \
+	fi
+	@rm -f Make.dep .depend
+
+-include Make.dep
+
diff --git a/nuttx/arch/avr/src/at91uc3/Make.defs b/nuttx/arch/avr/src/at91uc3/Make.defs
new file mode 100755
index 000000000..84ae09217
--- /dev/null
+++ b/nuttx/arch/avr/src/at91uc3/Make.defs
@@ -0,0 +1,57 @@
+############################################################################
+# arch/avr/src/at91uc3/Make.defs
+#
+#   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+# The start-up, "head", file
+
+HEAD_ASRC	= 
+
+# Common AVR/AVR32 files
+
+CMN_ASRCS	= 
+CMN_CSRCS	= up_assert.c up_blocktask.c up_copystate.c up_createstack.c \
+		  up_mdelay.c up_udelay.c up_exit.c up_idle.c up_initialize.c \
+		  up_initialstate.c up_interruptcontext.c up_modifyreg8.c \
+		  up_modifyreg16.c up_modifyreg32.c up_releasepending.c \
+		  up_releasestack.c up_reprioritizertr.c up_schedulesigaction.c \
+		  up_sigdeliver.c up_unblocktask.c up_usestack.c up_doirq.c
+
+# Required AT91UC3 files
+
+CHIP_ASRCS	=
+CHIP_CSRCS	= 
+
+# Configuration-dependent AT91UC3 files
+
+
diff --git a/nuttx/arch/avr/src/at91uc3/at91uc3_memorymap.h b/nuttx/arch/avr/src/at91uc3/at91uc3_memorymap.h
new file mode 100755
index 000000000..71a48de8b
--- /dev/null
+++ b/nuttx/arch/avr/src/at91uc3/at91uc3_memorymap.h
@@ -0,0 +1,62 @@
+/************************************************************************************
+ * arch/avr/src/at91uc3/at91uc3_memorymap.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************************************/
+
+#ifndef __ARCH_AVR_SRC_AT91UC3_AT91UC3_MEMORYMAP_H
+#define __ARCH_AVR_SRC_AT91UC3_AT91UC3_MEMORYMAP_H
+
+/************************************************************************************
+ * Included Files
+ ************************************************************************************/
+
+#include <nuttx/config.h>
+
+/************************************************************************************
+ * Pre-processor Definitions
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Types
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Data
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Functions
+ ************************************************************************************/
+
+#endif /* __ARCH_AVR_SRC_AT91UC3_AT91UC3_MEMORYMAP_H */
+
diff --git a/nuttx/arch/avr/src/at91uc3/chip.h b/nuttx/arch/avr/src/at91uc3/chip.h
new file mode 100755
index 000000000..c5133d6c1
--- /dev/null
+++ b/nuttx/arch/avr/src/at91uc3/chip.h
@@ -0,0 +1,75 @@
+/************************************************************************************
+ * arch/avr/src/at91uc3/chip.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************************************/
+
+#ifndef __ARCH_AVR_SRC_AT91UC3_CHIP_H
+#define __ARCH_AVR_SRC_AT91UC3_CHIP_H
+
+/************************************************************************************
+ * Included Files
+ ************************************************************************************/
+
+#include <nuttx/config.h>
+
+/************************************************************************************
+ * Pre-processor Definitions
+ ************************************************************************************/
+
+/* Get customizations for each supported chip */
+
+#if 0
+#else
+#  error "Unsupported AVR32 chip"
+#endif
+
+/* Include only the memory map.  Other chip hardware files should then include this
+ * file for the proper setup
+ */
+
+#include "atuc3_memorymap.h"
+
+/************************************************************************************
+ * Public Types
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Data
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Functions
+ ************************************************************************************/
+
+#endif /* __ARCH_AVR_SRC_AT91UC3_CHIP_H */
+
diff --git a/nuttx/arch/avr/src/avr32/up_assert.c b/nuttx/arch/avr/src/avr32/up_assert.c
new file mode 100644
index 000000000..ac273bb6b
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_assert.c
@@ -0,0 +1,319 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_assert.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Output debug info if stack dump is selected -- even if 
+ * debug is not selected.
+ */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+# undef  lldbg
+# define lldbg lib_lowprintf
+#endif
+
+/* The following is just intended to keep some ugliness out of the mainline
+ * code.  We are going to print the task name if:
+ *
+ *  CONFIG_TASK_NAME_SIZE > 0 &&    <-- The task has a name
+ *  (defined(CONFIG_DEBUG)    ||    <-- And the debug is enabled (lldbg used)
+ *   defined(CONFIG_ARCH_STACKDUMP) <-- Or lib_lowprintf() is used
+ */
+
+#undef CONFIG_PRINT_TASKNAME
+#if CONFIG_TASK_NAME_SIZE > 0 && (defined(CONFIG_DEBUG) || defined(CONFIG_ARCH_STACKDUMP))
+#  define CONFIG_PRINT_TASKNAME 1
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_getsp
+ ****************************************************************************/
+
+/* I don't know if the builtin to get SP is enabled */
+
+static inline uint32_t up_getsp(void)
+{
+# warning "Not implemented"
+  return 0;
+}
+
+/****************************************************************************
+ * Name: up_stackdump
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static void up_stackdump(uint32_t sp, uint32_t stack_base)
+{
+  uint32_t stack ;
+
+  for (stack = sp & ~0x1f; stack < stack_base; stack += 32)
+    {
+      uint32_t *ptr = (uint32_t*)stack;
+      lldbg("%08x: %08x %08x %08x %08x %08x %08x %08x %08x\n",
+             stack, ptr[0], ptr[1], ptr[2], ptr[3],
+             ptr[4], ptr[5], ptr[6], ptr[7]);
+    }
+}
+#else
+# define up_stackdump()
+#endif
+
+/****************************************************************************
+ * Name: up_registerdump
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static inline void up_registerdump(void)
+{
+  /* Are user registers available from interrupt processing? */
+
+  if (current_regs)
+    {
+      /* Yes.. dump the interrupt registers */
+
+# warning "Not implemented"
+    }
+}
+#else
+# define up_registerdump()
+#endif
+
+/****************************************************************************
+ * Name: up_dumpstate
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static void up_dumpstate(void)
+{
+  _TCB    *rtcb = (_TCB*)g_readytorun.head;
+  uint32_t sp   = up_getsp();
+  uint32_t ustackbase;
+  uint32_t ustacksize;
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  uint32_t istackbase;
+  uint32_t istacksize;
+#endif
+
+  /* Get the limits on the user stack memory */
+
+  if (rtcb->pid == 0)
+    {
+      ustackbase = g_heapbase - 4;
+      ustacksize = CONFIG_IDLETHREAD_STACKSIZE;
+    }
+  else
+    {
+      ustackbase = (uint32_t)rtcb->adj_stack_ptr;
+      ustacksize = (uint32_t)rtcb->adj_stack_size;
+    }
+
+  /* Get the limits on the interrupt stack memory */
+
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  istackbase = (uint32_t)&g_intstackbase;
+  istacksize = (CONFIG_ARCH_INTERRUPTSTACK & ~3) - 4;
+
+  /* Show interrupt stack info */
+
+  lldbg("sp:     %08x\n", sp);
+  lldbg("IRQ stack:\n");
+  lldbg("  base: %08x\n", istackbase);
+  lldbg("  size: %08x\n", istacksize);
+
+  /* Does the current stack pointer lie within the interrupt
+   * stack?
+   */
+
+  if (sp <= istackbase && sp > istackbase - istacksize)
+    {
+      /* Yes.. dump the interrupt stack */
+
+      up_stackdump(sp, istackbase);
+    }
+
+  /* Extract the user stack pointer if we are in an interrupt handler.
+   * If we are not in an interrupt handler.  Then sp is the user stack
+   * pointer (and the above range check should have failed).
+   */
+
+  if (current_regs)
+    {
+      sp = current_regs[REG_R13];
+      lldbg("sp:     %08x\n", sp);
+    }
+
+  lldbg("User stack:\n");
+  lldbg("  base: %08x\n", ustackbase);
+  lldbg("  size: %08x\n", ustacksize);
+
+  /* Dump the user stack if the stack pointer lies within the allocated user
+   * stack memory.
+   */
+
+  if (sp <= ustackbase && sp > ustackbase - ustacksize)
+    {
+      up_stackdump(sp, ustackbase);
+    }
+#else
+  lldbg("sp:         %08x\n", sp);
+  lldbg("stack base: %08x\n", ustackbase);
+  lldbg("stack size: %08x\n", ustacksize);
+
+  /* Dump the user stack if the stack pointer lies within the allocated user
+   * stack memory.
+   */
+
+  if (sp > ustackbase || sp <= ustackbase - ustacksize)
+    {
+      lldbg("ERROR: Stack pointer is not within allocated stack\n");
+    }
+  else
+    {
+      up_stackdump(sp, ustackbase);
+    }
+#endif
+
+  /* Then dump the registers (if available) */
+
+  up_registerdump();
+}
+#else
+# define up_dumpstate()
+#endif
+
+/****************************************************************************
+ * Name: _up_assert
+ ****************************************************************************/
+
+static void _up_assert(int errorcode) /* __attribute__ ((noreturn)) */
+{
+  /* Are we in an interrupt handler or the idle task? */
+
+  if (current_regs || ((_TCB*)g_readytorun.head)->pid == 0)
+    {
+       (void)irqsave();
+        for(;;)
+          {
+#ifdef CONFIG_ARCH_LEDS
+            up_ledon(LED_PANIC);
+            up_mdelay(250);
+            up_ledoff(LED_PANIC);
+            up_mdelay(250);
+#endif
+          }
+    }
+  else
+    {
+      exit(errorcode);
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_assert
+ ****************************************************************************/
+
+void up_assert(const uint8_t *filename, int lineno)
+{
+#ifdef CONFIG_PRINT_TASKNAME
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+#endif
+
+  up_ledon(LED_ASSERTION);
+#ifdef CONFIG_PRINT_TASKNAME
+  lldbg("Assertion failed at file:%s line: %d task: %s\n",
+        filename, lineno, rtcb->name);
+#else
+  lldbg("Assertion failed at file:%s line: %d\n",
+        filename, lineno);
+#endif
+  up_dumpstate();
+  _up_assert(EXIT_FAILURE);
+}
+
+/****************************************************************************
+ * Name: up_assert_code
+ ****************************************************************************/
+
+void up_assert_code(const uint8_t *filename, int lineno, int errorcode)
+{
+#ifdef CONFIG_PRINT_TASKNAME
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+#endif
+
+  up_ledon(LED_ASSERTION);
+#ifdef CONFIG_PRINT_TASKNAME
+  lldbg("Assertion failed at file:%s line: %d task: %s error code: %d\n",
+        filename, lineno, rtcb->name, errorcode);
+#else
+  lldbg("Assertion failed at file:%s line: %d error code: %d\n",
+        filename, lineno, errorcode);
+#endif
+  up_dumpstate();
+  _up_assert(errorcode);
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_blocktask.c b/nuttx/arch/avr/src/avr32/up_blocktask.c
new file mode 100755
index 000000000..5897825ca
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_blocktask.c
@@ -0,0 +1,168 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_blocktask.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_block_task
+ *
+ * Description:
+ *   The currently executing task at the head of
+ *   the ready to run list must be stopped.  Save its context
+ *   and move it to the inactive list specified by task_state.
+ *
+ * Inputs:
+ *   tcb: Refers to a task in the ready-to-run list (normally
+ *     the task at the head of the list).  It most be
+ *     stopped, its context saved and moved into one of the
+ *     waiting task lists.  It it was the task at the head
+ *     of the ready-to-run list, then a context to the new
+ *     ready to run task must be performed.
+ *   task_state: Specifies which waiting task list should be
+ *     hold the blocked task TCB.
+ *
+ ****************************************************************************/
+
+void up_block_task(_TCB *tcb, tstate_t task_state)
+{
+  /* Verify that the context switch can be performed */
+
+  if ((tcb->task_state < FIRST_READY_TO_RUN_STATE) ||
+      (tcb->task_state > LAST_READY_TO_RUN_STATE))
+    {
+      PANIC(OSERR_BADBLOCKSTATE);
+    }
+  else
+    {
+      _TCB *rtcb = (_TCB*)g_readytorun.head;
+      bool switch_needed;
+
+      /* Remove the tcb task from the ready-to-run list.  If we
+       * are blocking the task at the head of the task list (the
+       * most likely case), then a context switch to the next
+       * ready-to-run task is needed. In this case, it should
+       * also be true that rtcb == tcb.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Add the task to the specified blocked task list */
+
+      sched_addblocked(tcb, (tstate_t)task_state);
+
+      /* If there are any pending tasks, then add them to the g_readytorun
+       * task list now
+       */
+
+      if (g_pendingtasks.head)
+        {
+          switch_needed |= sched_mergepending();
+        }
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* Are we in an interrupt handler? */
+
+          if (current_regs)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current_regs into the OLD rtcb.
+               */
+
+               up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+
+              /* Then switch contexts */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* No, then we will need to perform the user context switch */
+
+          else
+            {
+              /* Switch context to the context of the task at the head of the
+               * ready to run list.
+               */
+
+               _TCB *nexttcb = (_TCB*)g_readytorun.head;
+               up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+              /* up_switchcontext forces a context switch to the task at the
+               * head of the ready-to-run list.  It does not 'return' in the
+               * normal sense.  When it does return, it is because the blocked
+               * task is again ready to run and has execution priority.
+               */
+           }
+        }
+    }
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_copystate.c b/nuttx/arch/avr/src/avr32/up_copystate.c
new file mode 100644
index 000000000..ef8d5f3cb
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_copystate.c
@@ -0,0 +1,86 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_copystate.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_copystate
+ ****************************************************************************/
+
+/* A little faster than most memcpy's */
+
+void up_copystate(uint32_t *dest, uint32_t *src)
+{
+  int i;
+
+  /* The state is copied from the stack to the TCB, but only a reference is
+   * passed to get the state from the TCB.  So the following check avoids
+   * copying the TCB save area onto itself:
+   */
+
+  if (src != dest)
+    {
+      for (i = 0; i < XCPTCONTEXT_REGS; i++)
+        {
+          *dest++ = *src++;
+        }
+    }
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_doirq.c b/nuttx/arch/avr/src/avr32/up_doirq.c
new file mode 100644
index 000000000..da3f244d6
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_doirq.c
@@ -0,0 +1,119 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_doirq.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <assert.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+uint32_t *up_doirq(int irq, uint32_t *regs)
+{
+  up_ledon(LED_INIRQ);
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
+  PANIC(OSERR_ERREXCEPTION);
+#else
+  /* Nested interrupts are not supported in this implementation.  If you want
+   * implemented nested interrupts, you would have to (1) change the way that
+   * current regs is handled and (2) the design associated with
+   * CONFIG_ARCH_INTERRUPTSTACK.
+   */
+
+  /* Current regs non-zero indicates that we are processing an interrupt;
+   * current_regs is also used to manage interrupt level context switches.
+   */
+
+  DEBUGASSERT(current_regs == NULL);
+  current_regs = regs;
+
+  /* Mask and acknowledge the interrupt */
+
+  up_maskack_irq(irq);
+
+  /* Deliver the IRQ */
+
+  irq_dispatch(irq, regs);
+
+  /* If a context switch occurred while processing the interrupt then
+   * current_regs may have change value.  If we return any value different
+   * from the input regs, then the lower level will know that a context
+   * switch occurred during interrupt processing.
+   */
+
+  regs = current_regs;
+
+  /* Indicate that we are no long in an interrupt handler */
+
+  current_regs = NULL;
+
+  /* Unmask the last interrupt (global interrupts are still disabled) */
+
+  up_enable_irq(irq);
+#endif
+  up_ledoff(LED_INIRQ);
+  return regs;
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_initialstate.c b/nuttx/arch/avr/src/avr32/up_initialstate.c
new file mode 100644
index 000000000..e6f606b6a
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_initialstate.c
@@ -0,0 +1,99 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_initialstate.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <nuttx/arch.h>
+
+#include "up_internal.h"
+#include "up_arch.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_initial_state
+ *
+ * Description:
+ *   A new thread is being started and a new TCB has been created. This
+ *   function is called to initialize the processor specific portions of the
+ *   new TCB.
+ *
+ *   This function must setup the intial architecture registers and/or stack
+ *   so that execution will begin at tcb->start  on the next context switch.
+ *
+ ****************************************************************************/
+
+void up_initial_state(_TCB *tcb)
+{
+  struct xcptcontext *xcp = &tcb->xcp;
+
+  /* Initialize the initial exception register context structure */
+
+  memset(xcp, 0, sizeof(struct xcptcontext));
+
+  /* Save the initial stack pointer */
+  /* Save the task entry point (stripping off the thumb bit) */
+
+# warning "Not implemented"
+
+  /* Enable or disable interrupts, based on user configuration */
+
+# ifdef CONFIG_SUPPRESS_INTERRUPTS
+#   warning "Not implemented"
+# endif
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_releasepending.c b/nuttx/arch/avr/src/avr32/up_releasepending.c
new file mode 100755
index 000000000..cf8ac5590
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_releasepending.c
@@ -0,0 +1,131 @@
+/****************************************************************************
+ *  arch/avr/src/avr32/up_releasepending.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_release_pending
+ *
+ * Description:
+ *   Release and ready-to-run tasks that have
+ *   collected in the pending task list.  This can call a
+ *   context switch if a new task is placed at the head of
+ *   the ready to run list.
+ *
+ ****************************************************************************/
+
+void up_release_pending(void)
+{
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+
+  slldbg("From TCB=%p\n", rtcb);
+
+  /* Merge the g_pendingtasks list into the g_readytorun task list */
+
+  /* sched_lock(); */
+  if (sched_mergepending())
+    {
+      /* The currently active task has changed!  We will need to
+       * switch contexts.  First check if we are operating in
+       * interrupt context:
+       */
+
+      if (current_regs)
+        {
+          /* Yes, then we have to do things differently.
+           * Just copy the current_regs into the OLD rtcb.
+           */
+
+           up_savestate(rtcb->xcp.regs);
+
+          /* Restore the exception context of the rtcb at the (new) head 
+           * of the g_readytorun task list.
+           */
+
+          rtcb = (_TCB*)g_readytorun.head;
+          slldbg("New Active Task TCB=%p\n", rtcb);
+
+          /* Then switch contexts */
+
+          up_restorestate(rtcb->xcp.regs);
+        }
+
+      /* No, then we will need to perform the user context switch */
+
+      else
+        {
+          /* Switch context to the context of the task at the head of the
+           * ready to run list.
+           */
+
+          _TCB *nexttcb = (_TCB*)g_readytorun.head;
+          up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+          /* up_switchcontext forces a context switch to the task at the
+           * head of the ready-to-run list.  It does not 'return' in the
+           * normal sense.  When it does return, it is because the blocked
+           * task is again ready to run and has execution priority.
+           */
+        }
+    }
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_reprioritizertr.c b/nuttx/arch/avr/src/avr32/up_reprioritizertr.c
new file mode 100755
index 000000000..967ea025a
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_reprioritizertr.c
@@ -0,0 +1,182 @@
+/****************************************************************************
+ *  arch/avr/src/avr32/up_reprioritizertr.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_reprioritize_rtr
+ *
+ * Description:
+ *   Called when the priority of a running or
+ *   ready-to-run task changes and the reprioritization will 
+ *   cause a context switch.  Two cases:
+ *
+ *   1) The priority of the currently running task drops and the next
+ *      task in the ready to run list has priority.
+ *   2) An idle, ready to run task's priority has been raised above the
+ *      the priority of the current, running task and it now has the
+ *      priority.
+ *
+ * Inputs:
+ *   tcb: The TCB of the task that has been reprioritized
+ *   priority: The new task priority
+ *
+ ****************************************************************************/
+
+void up_reprioritize_rtr(_TCB *tcb, uint8_t priority)
+{
+  /* Verify that the caller is sane */
+
+  if (tcb->task_state < FIRST_READY_TO_RUN_STATE ||
+      tcb->task_state > LAST_READY_TO_RUN_STATE ||
+      priority < SCHED_PRIORITY_MIN || 
+      priority > SCHED_PRIORITY_MAX)
+    {
+       PANIC(OSERR_BADREPRIORITIZESTATE);
+    }
+  else
+    {
+      _TCB *rtcb = (_TCB*)g_readytorun.head;
+      bool switch_needed;
+
+      slldbg("TCB=%p PRI=%d\n", tcb, priority);
+
+      /* Remove the tcb task from the ready-to-run list.
+       * sched_removereadytorun will return true if we just
+       * remove the head of the ready to run list.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Setup up the new task priority */
+
+      tcb->sched_priority = (uint8_t)priority;
+
+      /* Return the task to the specified blocked task list.
+       * sched_addreadytorun will return true if the task was
+       * added to the new list.  We will need to perform a context
+       * switch only if the EXCLUSIVE or of the two calls is non-zero
+       * (i.e., one and only one the calls changes the head of the
+       * ready-to-run list).
+       */
+
+      switch_needed ^= sched_addreadytorun(tcb);
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* If we are going to do a context switch, then now is the right
+           * time to add any pending tasks back into the ready-to-run list.
+           * task list now
+           */
+
+          if (g_pendingtasks.head)
+            {
+              sched_mergepending();
+            }
+
+         /* Are we in an interrupt handler? */
+
+          if (current_regs)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current_regs into the OLD rtcb.
+               */
+
+               up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+              slldbg("New Active Task TCB=%p\n", rtcb);
+
+              /* Then switch contexts */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* No, then we will need to perform the user context switch */
+
+          else
+            {
+              /* Switch context to the context of the task at the head of the
+               * ready to run list.
+               */
+
+              _TCB *nexttcb = (_TCB*)g_readytorun.head;
+              up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+              /* up_switchcontext forces a context switch to the task at the
+               * head of the ready-to-run list.  It does not 'return' in the
+               * normal sense.  When it does return, it is because the blocked
+               * task is again ready to run and has execution priority.
+               */
+            }
+        }
+    }
+}
+
diff --git a/nuttx/arch/avr/src/avr32/up_schedulesigaction.c b/nuttx/arch/avr/src/avr32/up_schedulesigaction.c
new file mode 100644
index 000000000..7f7dff6a3
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_schedulesigaction.c
@@ -0,0 +1,201 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_schedulesigaction.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+
+#include "psr.h"
+#include "os_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+#ifndef CONFIG_DISABLE_SIGNALS
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_schedule_sigaction
+ *
+ * Description:
+ *   This function is called by the OS when one or more
+ *   signal handling actions have been queued for execution.
+ *   The architecture specific code must configure things so
+ *   that the 'igdeliver' callback is executed on the thread
+ *   specified by 'tcb' as soon as possible.
+ *
+ *   This function may be called from interrupt handling logic.
+ *
+ *   This operation should not cause the task to be unblocked
+ *   nor should it cause any immediate execution of sigdeliver.
+ *   Typically, a few cases need to be considered:
+ *
+ *   (1) This function may be called from an interrupt handler
+ *       During interrupt processing, all xcptcontext structures
+ *       should be valid for all tasks.  That structure should
+ *       be modified to invoke sigdeliver() either on return
+ *       from (this) interrupt or on some subsequent context
+ *       switch to the recipient task.
+ *   (2) If not in an interrupt handler and the tcb is NOT
+ *       the currently executing task, then again just modify
+ *       the saved xcptcontext structure for the recipient
+ *       task so it will invoke sigdeliver when that task is
+ *       later resumed.
+ *   (3) If not in an interrupt handler and the tcb IS the
+ *       currently executing task -- just call the signal
+ *       handler now.
+ *
+ ****************************************************************************/
+
+void up_schedule_sigaction(_TCB *tcb, sig_deliver_t sigdeliver)
+{
+  /* Refuse to handle nested signal actions */
+
+  sdbg("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver);
+
+  if (!tcb->xcp.sigdeliver)
+    {
+      irqstate_t flags;
+
+      /* Make sure that interrupts are disabled */
+
+      flags = irqsave();
+
+      /* First, handle some special cases when the signal is
+       * being delivered to the currently executing task.
+       */
+
+      sdbg("rtcb=0x%p current_regs=0x%p\n", g_readytorun.head, current_regs);
+
+      if (tcb == (_TCB*)g_readytorun.head)
+        {
+          /* CASE 1:  We are not in an interrupt handler and
+           * a task is signalling itself for some reason.
+           */
+
+          if (!current_regs)
+            {
+              /* In this case just deliver the signal now. */
+
+              sigdeliver(tcb);
+            }
+
+          /* CASE 2:  We are in an interrupt handler AND the
+           * interrupted task is the same as the one that
+           * must receive the signal, then we will have to modify
+           * the return state as well as the state in the TCB.
+           *
+           * Hmmm... there looks like a latent bug here: The following
+           * logic would fail in the strange case where we are in an
+           * interrupt handler, the thread is signalling itself, but
+           * a context switch to another task has occurred so that
+           * current_regs does not refer to the thread at g_readytorun.head!
+           */
+
+          else
+            {
+              /* Save registers that must be protected while the signal handler
+               * runs. These will be restored by the signal trampoline after
+               * the signal(s) have been delivered.
+               */
+
+              tcb->xcp.sigdeliver       = sigdeliver;
+#warning "Not implemented"
+
+              /* Then set up to vector to the trampoline with interrupts
+               * disabled
+               */
+
+#warning "Not implemented"
+
+              /* And make sure that the saved context in the TCB
+               * is the same as the interrupt return context.
+               */
+
+              up_savestate(tcb->xcp.regs);
+            }
+        }
+
+      /* Otherwise, we are (1) signaling a task is not running
+       * from an interrupt handler or (2) we are not in an
+       * interrupt handler and the running task is signalling
+       * some non-running task.
+       */
+
+      else
+        {
+          /* Save registers that must be protected while the signal handler
+           * runs. These will be restored by the signal trampoline after
+           * the signals have been delivered.
+           */
+
+          tcb->xcp.sigdeliver       = sigdeliver;
+#warning "Not implemented"
+
+          /* Then set up to vector to the trampoline with interrupts
+           * disabled
+           */
+
+#warning "Not implemented"
+        }
+
+      irqrestore(flags);
+    }
+}
+
+#endif /* !CONFIG_DISABLE_SIGNALS */
+
diff --git a/nuttx/arch/avr/src/avr32/up_sigdeliver.c b/nuttx/arch/avr/src/avr32/up_sigdeliver.c
new file mode 100644
index 000000000..2159ce0c0
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_sigdeliver.c
@@ -0,0 +1,139 @@
+/****************************************************************************
+ * arch/avr/src/avr32/up_sigdeliver.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+#ifndef CONFIG_DISABLE_SIGNALS
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_sigdeliver
+ *
+ * Description:
+ *   This is the a signal handling trampoline.  When a signal action was
+ *   posted.  The task context was mucked with and forced to branch to this
+ *   location with interrupts disabled.
+ *
+ ****************************************************************************/
+
+void up_sigdeliver(void)
+{
+  _TCB  *rtcb = (_TCB*)g_readytorun.head;
+  uint32_t regs[XCPTCONTEXT_REGS];
+  sig_deliver_t sigdeliver;
+
+  /* Save the errno.  This must be preserved throughout the signal handling
+   * so that the user code final gets the correct errno value (probably EINTR).
+   */
+
+  int saved_errno = rtcb->pterrno;
+
+  up_ledon(LED_SIGNAL);
+
+  sdbg("rtcb=%p sigdeliver=%p sigpendactionq.head=%p\n",
+        rtcb, rtcb->xcp.sigdeliver, rtcb->sigpendactionq.head);
+  ASSERT(rtcb->xcp.sigdeliver != NULL);
+
+  /* Save the real return state on the stack. */
+
+  up_copystate(regs, rtcb->xcp.regs);
+#warning "Not Implemented"
+
+  /* Get a local copy of the sigdeliver function pointer. We do this so tha
+   * we can nullify the sigdeliver function point in the TCB and accept more
+   * signal deliveries while processing the current pending signals.
+   */
+
+  sigdeliver           = rtcb->xcp.sigdeliver;
+  rtcb->xcp.sigdeliver = NULL;
+
+  /* Then restore the task interrupt state */
+
+  irqrestore((uint16_t)regs[REG_PRIMASK]);
+
+  /* Deliver the signals */
+
+  sigdeliver(rtcb);
+
+  /* Output any debug messaged BEFORE restoreing errno
+   * (becuase they may alter errno), then restore the
+   * original errno that is needed by the user logic
+   * (it is probably EINTR).
+   */
+
+  sdbg("Resuming\n");
+  rtcb->pterrno = saved_errno;
+
+  /* Then restore the correct state for this thread of
+   * execution.
+   */
+
+  up_ledoff(LED_SIGNAL);
+  up_fullcontextrestore(regs);
+}
+
+#endif /* !CONFIG_DISABLE_SIGNALS */
+
diff --git a/nuttx/arch/avr/src/avr32/up_unblocktask.c b/nuttx/arch/avr/src/avr32/up_unblocktask.c
new file mode 100755
index 000000000..43b6e5830
--- /dev/null
+++ b/nuttx/arch/avr/src/avr32/up_unblocktask.c
@@ -0,0 +1,158 @@
+/****************************************************************************
+ *  arch/avr/src/avr32/up_unblocktask.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "clock_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_unblock_task
+ *
+ * Description:
+ *   A task is currently in an inactive task list
+ *   but has been prepped to execute.  Move the TCB to the
+ *   ready-to-run list, restore its context, and start execution.
+ *
+ * Inputs:
+ *   tcb: Refers to the tcb to be unblocked.  This tcb is
+ *     in one of the waiting tasks lists.  It must be moved to
+ *     the ready-to-run list and, if it is the highest priority
+ *     ready to run taks, executed.
+ *
+ ****************************************************************************/
+
+void up_unblock_task(_TCB *tcb)
+{
+  /* Verify that the context switch can be performed */
+
+  if ((tcb->task_state < FIRST_BLOCKED_STATE) ||
+      (tcb->task_state > LAST_BLOCKED_STATE))
+    {
+      PANIC(OSERR_BADUNBLOCKSTATE);
+    }
+  else
+    {
+      _TCB *rtcb = (_TCB*)g_readytorun.head;
+
+      /* Remove the task from the blocked task list */
+
+      sched_removeblocked(tcb);
+
+      /* Reset its timeslice.  This is only meaningful for round
+       * robin tasks but it doesn't here to do it for everything
+       */
+
+#if CONFIG_RR_INTERVAL > 0
+      tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+#endif
+
+      /* Add the task in the correct location in the prioritized
+       * g_readytorun task list
+       */
+
+      if (sched_addreadytorun(tcb))
+        {
+          /* The currently active task has changed! We need to do
+           * a context switch to the new task.
+           *
+           * Are we in an interrupt handler? 
+           */
+
+          if (current_regs)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current_regs into the OLD rtcb.
+               */
+
+               up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+
+              /* Then switch contexts */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* No, then we will need to perform the user context switch */
+
+          else
+            {
+              /* Switch context to the context of the task at the head of the
+               * ready to run list.
+               */
+
+               _TCB *nexttcb = (_TCB*)g_readytorun.head;
+               up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
+
+              /* up_switchcontext forces a context switch to the task at the
+               * head of the ready-to-run list.  It does not 'return' in the
+               * normal sense.  When it does return, it is because the blocked
+               * task is again ready to run and has execution priority.
+               */
+           }
+        }
+    }
+}
+
diff --git a/nuttx/arch/avr/src/common/up_allocateheap.c b/nuttx/arch/avr/src/common/up_allocateheap.c
new file mode 100644
index 000000000..62be64338
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_allocateheap.c
@@ -0,0 +1,83 @@
+/****************************************************************************
+ * arch/avr/src/common/up_allocateheap.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_allocate_heap
+ *
+ * Description:
+ *   The heap may be statically allocated by
+ *   defining CONFIG_HEAP_BASE and CONFIG_HEAP_SIZE.  If these
+ *   are not defined, then this function will be called to
+ *   dynamically set aside the heap region.
+ *
+ ****************************************************************************/
+
+void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
+{
+  up_ledon(LED_HEAPALLOCATE);
+  *heap_start = (FAR void*)g_heapbase;
+  *heap_size = CONFIG_DRAM_END - g_heapbase;
+}
diff --git a/nuttx/arch/avr/src/common/up_arch.h b/nuttx/arch/avr/src/common/up_arch.h
new file mode 100644
index 000000000..16a303c5a
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_arch.h
@@ -0,0 +1,90 @@
+/****************************************************************************
+ * arch/avr/src/common/up_arch.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_AVR_SRC_COMMON_UP_ARCH_H
+#define __ARCH_AVR_SRC_COMMON_UP_ARCH_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#ifndef __ASSEMBLY__
+# include <stdint.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+# define getreg8(a)           (*(volatile uint8_t *)(a))
+# define putreg8(v,a)         (*(volatile uint8_t *)(a) = (v))
+# define getreg16(a)          (*(volatile uint16_t *)(a))
+# define putreg16(v,a)        (*(volatile uint16_t *)(a) = (v))
+# define getreg32(a)          (*(volatile uint32_t *)(a))
+# define putreg32(v,a)        (*(volatile uint32_t *)(a) = (v))
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+/* Atomic modification of registers */
+
+EXTERN void modifyreg8(unsigned int addr, uint8_t clearbits, uint8_t setbits);
+EXTERN void modifyreg16(unsigned int addr, uint16_t clearbits, uint16_t setbits);
+EXTERN void modifyreg32(unsigned int addr, uint32_t clearbits, uint32_t setbits);
+
+#undef EXTERN
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ARCH_AVR_SRC_COMMON_UP_ARCH_H */
+
diff --git a/nuttx/arch/avr/src/common/up_createstack.c b/nuttx/arch/avr/src/common/up_createstack.c
new file mode 100644
index 000000000..7b83357b6
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_createstack.c
@@ -0,0 +1,138 @@
+/****************************************************************************
+ * arch/avr/src/common/up_createstack.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_create_stack
+ *
+ * Description:
+ *   Allocate a stack for a new thread and setup
+ *   up stack-related information in the TCB.
+ *
+ *   The following TCB fields must be initialized:
+ *   adj_stack_size: Stack size after adjustment for hardware,
+ *     processor, etc.  This value is retained only for debug
+ *     purposes.
+ *   stack_alloc_ptr: Pointer to allocated stack
+ *   adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The
+ *     initial value of the stack pointer.
+ *
+ * Inputs:
+ *   tcb: The TCB of new task
+ *   stack_size:  The requested stack size.  At least this much
+ *     must be allocated.
+ ****************************************************************************/
+
+int up_create_stack(_TCB *tcb, size_t stack_size)
+{
+  if (tcb->stack_alloc_ptr &&
+      tcb->adj_stack_size != stack_size)
+    {
+      sched_free(tcb->stack_alloc_ptr);
+      tcb->stack_alloc_ptr = NULL;
+    }
+
+   if (!tcb->stack_alloc_ptr)
+     {
+#ifdef CONFIG_DEBUG
+       tcb->stack_alloc_ptr = (uint32_t*)zalloc(stack_size);
+#else
+       tcb->stack_alloc_ptr = (uint32_t*)malloc(stack_size);
+#endif
+     }
+
+   if (tcb->stack_alloc_ptr)
+     {
+       size_t top_of_stack;
+       size_t size_of_stack;
+
+       /* The AVR32 uses a push-down stack:  the stack grows
+	* toward loweraddresses in memory.  The stack pointer
+	* register, points to the lowest, valid work address
+	* (the "top" of the stack).  Items on the stack are
+	* referenced as positive word offsets from sp.
+	*/
+
+       top_of_stack = (uint32_t)tcb->stack_alloc_ptr + stack_size - 4;
+
+       /* The AVR32 stack must be aligned at word (4 byte)
+	* boundaries. If necessary top_of_stack must be rounded
+	* down to the next boundary
+	*/
+
+       top_of_stack &= ~3;
+       size_of_stack = top_of_stack - (uint32_t)tcb->stack_alloc_ptr + 4;
+
+       /* Save the adjusted stack values in the _TCB */
+
+       tcb->adj_stack_ptr  = (uint32_t*)top_of_stack;
+       tcb->adj_stack_size = size_of_stack;
+
+       up_ledon(LED_STACKCREATED);
+       return OK;
+     }
+
+   return ERROR;
+}
diff --git a/nuttx/arch/avr/src/common/up_exit.c b/nuttx/arch/avr/src/common/up_exit.c
new file mode 100644
index 000000000..d7104c5da
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_exit.c
@@ -0,0 +1,174 @@
+/****************************************************************************
+ * arch/avr/src/common/up_exit.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+#ifdef CONFIG_DUMP_ON_EXIT
+#include <nuttx/fs.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _up_dumponexit
+ *
+ * Description:
+ *   Dump the state of all tasks whenever on task exits.  This is debug
+ *   instrumentation that was added to check file-related reference counting
+ *   but could be useful again sometime in the future.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_DUMP_ON_EXIT) && defined(CONFIG_DEBUG)
+static void _up_dumponexit(FAR _TCB *tcb, FAR void *arg)
+{
+#if CONFIG_NFILE_DESCRIPTORS > 0 || CONFIG_NFILE_STREAMS > 0
+  int i;
+#endif
+
+  sdbg("  TCB=%p name=%s pid=%d\n", tcb, tcb->argv[0], tcb->pid);
+  sdbg("    priority=%d state=%d\n", tcb->sched_priority, tcb->task_state);
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+  if (tcb->filelist)
+    {
+      sdbg("    filelist refcount=%d\n",
+           tcb->filelist->fl_crefs);
+
+      for (i = 0; i < CONFIG_NFILE_DESCRIPTORS; i++)
+        {
+          struct inode *inode = tcb->filelist->fl_files[i].f_inode;
+          if (inode)
+            {
+              sdbg("      fd=%d refcount=%d\n",
+                   i, inode->i_crefs);
+            }
+        }
+    }
+#endif
+
+#if CONFIG_NFILE_STREAMS > 0
+  if (tcb->streams)
+    {
+      sdbg("    streamlist refcount=%d\n",
+           tcb->streams->sl_crefs);
+
+      for (i = 0; i < CONFIG_NFILE_STREAMS; i++)
+        {
+          struct file_struct *filep = &tcb->streams->sl_streams[i];
+          if (filep->fs_filedes >= 0)
+            {
+#if CONFIG_STDIO_BUFFER_SIZE > 0
+              sdbg("      fd=%d nbytes=%d\n",
+                   filep->fs_filedes,
+                  filep->fs_bufpos - filep->fs_bufstart);
+#else
+              sdbg("      fd=%d\n", filep->fs_filedes);
+#endif
+            }
+        }
+    }
+#endif
+}
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _exit
+ *
+ * Description:
+ *   This function causes the currently executing task to cease
+ *   to exist.  This is a special case of task_delete() where the task to
+ *   be deleted is the currently executing task.  It is more complex because
+ *   a context switch must be perform to the next ready to run task.
+ *
+ ****************************************************************************/
+
+void _exit(int status)
+{
+  _TCB* tcb;
+
+  /* Disable interrupts.  They will be restored when the next
+   * task is started.
+   */
+
+  (void)irqsave();
+
+  slldbg("TCB=%p exitting\n", g_readytorun.head);
+
+#if defined(CONFIG_DUMP_ON_EXIT) && defined(CONFIG_DEBUG)
+  slldbg("Other tasks:\n");
+  sched_foreach(_up_dumponexit, NULL);
+#endif
+
+  /* Destroy the task at the head of the ready to run list. */
+
+  (void)task_deletecurrent();
+
+  /* Now, perform the context switch to the new ready-to-run task at the
+   * head of the list.
+   */
+
+  tcb = (_TCB*)g_readytorun.head;
+
+  /* Then switch contexts */
+
+  up_fullcontextrestore(tcb->xcp.regs);
+}
+
diff --git a/nuttx/arch/avr/src/common/up_idle.c b/nuttx/arch/avr/src/common/up_idle.c
new file mode 100644
index 000000000..2854956cd
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_idle.c
@@ -0,0 +1,87 @@
+/****************************************************************************
+ *  arch/avr/src/common/up_idle.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <nuttx/arch.h>
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_idle
+ *
+ * Description:
+ *   up_idle() is the logic that will be executed when their
+ *   is no other ready-to-run task.  This is processor idle
+ *   time and will continue until some interrupt occurs to
+ *   cause a context switch from the idle task.
+ *
+ *   Processing in this state may be processor-specific. e.g.,
+ *   this is where power management operations might be
+ *   performed.
+ *
+ ****************************************************************************/
+
+void up_idle(void)
+{
+#if defined(CONFIG_SUPPRESS_INTERRUPTS) || defined(CONFIG_SUPPRESS_TIMER_INTS)
+  /* If the system is idle and there are no timer interrupts,
+   * then process "fake" timer interrupts. Hopefully, something
+   * will wake up.
+   */
+
+  sched_process_timer();
+#endif
+}
+
diff --git a/nuttx/arch/avr/src/common/up_initialize.c b/nuttx/arch/avr/src/common/up_initialize.c
new file mode 100644
index 000000000..fde474ec6
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_initialize.c
@@ -0,0 +1,170 @@
+/****************************************************************************
+ * arch/avr/src/common/up_initialize.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/fs.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_calibratedelay
+ *
+ * Description:
+ *   Delay loops are provided for short timing loops.  This function, if
+ *   enabled, will just wait for 100 seconds.  Using a stopwatch, you can
+ *   can then determine if the timing loops are properly calibrated.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_ARCH_CALIBRATION) && defined(CONFIG_DEBUG)
+static void up_calibratedelay(void)
+{
+  int i;
+  lldbg("Beginning 100s delay\n");
+  for (i = 0; i < 100; i++)
+    {
+      up_mdelay(1000);
+    }
+  lldbg("End 100s delay\n");
+}
+#else
+# define up_calibratedelay()
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_initialize
+ *
+ * Description:
+ *   up_initialize will be called once during OS initialization after the
+ *   basic OS services have been initialized.  The architecture specific
+ *   details of initializing the OS will be handled here.  Such things as
+ *   setting up interrupt service routines, starting the clock, and
+ *   registering device drivers are some of the things that are different
+ *   for each processor and hardware platform.
+ *
+ *   up_initialize is called after the OS initialized but before the user
+ *   initialization logic has been started and before the libraries have
+ *   been initialized.  OS services and driver services are available.
+ *
+ ****************************************************************************/
+
+void up_initialize(void)
+{
+  /* Initialize global variables */
+
+  current_regs = NULL;
+
+  /* Calibrate the timing loop */
+
+  up_calibratedelay();
+
+  /* Add any extra memory fragments to the memory manager */
+
+  up_addregion();
+
+  /* Initialize the interrupt subsystem */
+
+  up_irqinitialize();
+
+  /* Initialize the DMA subsystem if the weak function stm32_dmainitialize has been
+   * brought into the build
+   */
+
+#ifdef CONFIG_ARCH_DMA
+#ifdef CONFIG_HAVE_WEAKFUNCTIONS
+  if (up_dmainitialize)
+#endif
+    {
+      up_dmainitialize();
+    }
+#endif
+
+  /* Initialize the system timer interrupt */
+
+#if !defined(CONFIG_SUPPRESS_INTERRUPTS) && !defined(CONFIG_SUPPRESS_TIMER_INTS)
+  up_timerinit();
+#endif
+
+  /* Register devices */
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+  devnull_register();   /* Standard /dev/null */
+#endif
+
+  /* Initialize the serial device driver */
+
+#ifdef CONFIG_USE_SERIALDRIVER
+  up_serialinit();
+#elif defined(CONFIG_DEV_LOWCONSOLE)
+  lowconsole_init();
+#endif
+
+  /* Initialize the netwok */
+
+  up_netinitialize();
+
+  /* Initialize USB */
+
+  up_usbinitialize();
+
+  up_ledon(LED_IRQSENABLED);
+}
+
diff --git a/nuttx/arch/avr/src/common/up_internal.h b/nuttx/arch/avr/src/common/up_internal.h
new file mode 100644
index 000000000..2468326ee
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_internal.h
@@ -0,0 +1,245 @@
+/****************************************************************************
+ * arch/avr/src/common/up_internal.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __UP_INTERNAL_H
+#define __UP_INTERNAL_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#  include <stdint.h>
+#endif
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Bring-up debug configurations.  These are here (vs defconfig)
+ * because these should only be controlled during low level
+ * board bring-up and not part of normal platform configuration.
+ */
+
+#undef  CONFIG_SUPPRESS_INTERRUPTS    /* DEFINED: Do not enable interrupts */
+#undef  CONFIG_SUPPRESS_TIMER_INTS    /* DEFINED: No timer */
+#undef  CONFIG_SUPPRESS_SERIAL_INTS   /* DEFINED: Console will poll */
+#undef  CONFIG_SUPPRESS_UART_CONFIG   /* DEFINED: Do not reconfig UART */
+#undef  CONFIG_DUMP_ON_EXIT           /* DEFINED: Dump task state on exit */
+
+/* Determine which (if any) console driver to use */
+
+#if CONFIG_NFILE_DESCRIPTORS == 0 || defined(CONFIG_DEV_LOWCONSOLE)
+#  undef CONFIG_USE_SERIALDRIVER
+#  undef CONFIG_USE_EARLYSERIALINIT
+#elif defined(CONFIG_DEV_CONSOLE) && CONFIG_NFILE_DESCRIPTORS > 0
+#  define CONFIG_USE_SERIALDRIVER 1
+#  define CONFIG_USE_EARLYSERIALINIT 1
+#endif
+
+/* Check if an interrupt stack size is configured */
+
+#ifndef CONFIG_ARCH_INTERRUPTSTACK
+# define CONFIG_ARCH_INTERRUPTSTACK 0
+#endif
+
+/* Macros to handle saving and restore interrupt state.  The state is copied
+ * from the stack to the TCB, but only a referenced is passed to get the 
+ * state from the TCB.
+ */
+
+#define up_savestate(regs)    up_copystate(regs, current_regs)
+#define up_restorestate(regs) (current_regs = regs)
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+typedef void (*up_vector_t)(void);
+#endif
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+/* This holds a references to the current interrupt level
+ * register storage structure.  If is non-NULL only during
+ * interrupt processing.
+ */
+
+extern uint32_t *current_regs;
+
+/* This is the beginning of heap as provided from up_head.S.
+ * This is the first address in DRAM after the loaded
+ * program+bss+idle stack.  The end of the heap is
+ * CONFIG_DRAM_END
+ */
+
+extern uint32_t g_heapbase;
+
+/* Address of the saved user stack pointer */
+
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+extern void g_intstackbase;
+#endif
+
+/* These 'addresses' of these values are setup by the linker script.  They are
+ * not actual uint32_t storage locations! They are only used meaningfully in the
+ * following way:
+ *
+ *  - The linker script defines, for example, the symbol_sdata.
+ *  - The declareion extern uint32_t _sdata; makes C happy.  C will believe
+ *    that the value _sdata is the address of a uint32_t variable _data (it is
+ *    not!).
+ *  - We can recoved the linker value then by simply taking the address of
+ *    of _data.  like:  uint32_t *pdata = &_sdata;
+ */
+
+extern uint32_t _stext;           /* Start of .text */
+extern uint32_t _etext;           /* End_1 of .text + .rodata */
+extern const uint32_t _eronly;    /* End+1 of read only section (.text + .rodata) */
+extern uint32_t _sdata;           /* Start of .data */
+extern uint32_t _edata;           /* End+1 of .data */
+extern uint32_t _sbss;            /* Start of .bss */
+extern uint32_t _ebss;            /* End+1 of .bss */
+#endif
+
+/****************************************************************************
+ * Inline Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* Defined in files with the same name as the function */
+
+extern void up_boot(void);
+extern void up_copystate(uint32_t *dest, uint32_t *src);
+extern void up_decodeirq(uint32_t *regs);
+extern void up_irqinitialize(void);
+#ifdef CONFIG_ARCH_DMA
+extern void weak_function up_dmainitialize(void);
+#endif
+extern int  up_saveusercontext(uint32_t *saveregs);
+extern void up_fullcontextrestore(uint32_t *restoreregs) __attribute__ ((noreturn));
+extern void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
+extern void up_sigdeliver(void);
+extern int  up_timerisr(int irq, uint32_t *regs);
+extern void up_lowputc(char ch);
+extern void up_puts(const char *str);
+extern void up_lowputs(const char *str);
+extern uint32_t *up_doirq(int irq, uint32_t *regs);
+extern int  up_svcall(int irq, FAR void *context);
+extern int  up_hardfault(int irq, FAR void *context);
+#ifdef CONFIG_PAGING
+extern void up_pginitialize(void);
+extern uint32_t *up_va2pte(uintptr_t vaddr);
+#else /* CONFIG_PAGING */
+# define up_pginitialize()
+#endif /* CONFIG_PAGING */
+
+/* Defined in up_allocateheap.c */
+
+#if CONFIG_MM_REGIONS > 1
+void up_addregion(void);
+#else
+# define up_addregion()
+#endif
+
+/* Defined in up_serial.c */
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+extern void up_earlyserialinit(void);
+extern void up_serialinit(void);
+#else
+# define up_earlyserialinit()
+# define up_serialinit()
+#endif
+
+/* Defined in drivers/lowconsole.c */
+
+#ifdef CONFIG_DEV_LOWCONSOLE
+extern void lowconsole_init(void);
+#else
+# define lowconsole_init()
+#endif
+
+/* Defined in up_timerisr.c */
+
+extern void up_timerinit(void);
+
+/* Defined in up_irq.c */
+
+extern void up_maskack_irq(int irq);
+
+/* Defined in board/up_leds.c */
+
+#ifdef CONFIG_ARCH_LEDS
+extern void up_ledinit(void);
+extern void up_ledon(int led);
+extern void up_ledoff(int led);
+#else
+# define up_ledinit()
+# define up_ledon(led)
+# define up_ledoff(led)
+#endif
+
+/* Defined in board/up_network.c */
+
+#ifdef CONFIG_NET
+extern void up_netinitialize(void);
+#else
+# define up_netinitialize()
+#endif
+
+/* Defined in board/up_ethernet.c */
+
+#ifdef CONFIG_USBDEV
+extern void up_usbinitialize(void);
+extern void up_usbuninitialize(void);
+#else
+# define up_usbinitialize()
+# define up_usbuninitialize()
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#endif  /* __UP_INTERNAL_H */
+
diff --git a/nuttx/arch/avr/src/common/up_interruptcontext.c b/nuttx/arch/avr/src/common/up_interruptcontext.c
new file mode 100644
index 000000000..c1bfb0e4d
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_interruptcontext.c
@@ -0,0 +1,70 @@
+/****************************************************************************
+ *  arch/avr/src/common/up_interruptcontext.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <nuttx/arch.h>
+#include <nuttx/irq.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_interrupt_context
+ *
+ * Description: Return true is we are currently executing in
+ * the interrupt handler context.
+ ****************************************************************************/
+
+bool up_interrupt_context(void)
+{
+   return current_regs != NULL;
+}
diff --git a/nuttx/arch/avr/src/common/up_lowputs.c b/nuttx/arch/avr/src/common/up_lowputs.c
new file mode 100644
index 000000000..5695b806a
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_lowputs.c
@@ -0,0 +1,75 @@
+/****************************************************************************
+ * arch/avr/src/common/up_lowputs.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_lowputs
+ *
+ * Description:
+ *   This is a low-level helper function used to support debug.
+ *
+ ****************************************************************************/
+
+void up_lowputs(const char *str)
+{
+  while(*str)
+    {
+      up_lowputc(*str++);
+    }
+}
+
diff --git a/nuttx/arch/avr/src/common/up_mdelay.c b/nuttx/arch/avr/src/common/up_mdelay.c
new file mode 100644
index 000000000..3fb76a058
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_mdelay.c
@@ -0,0 +1,91 @@
+/****************************************************************************
+ *  arch/avr/src/common/up_mdelay.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/arch.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_mdelay
+ *
+ * Description:
+ *   Delay inline for the requested number of milliseconds.
+ *   *** NOT multi-tasking friendly ***
+ *
+ * ASSUMPTIONS:
+ *   The setting CONFIG_BOARD_LOOPSPERMSEC has been calibrated
+ *
+ ****************************************************************************/
+
+void up_mdelay(unsigned int milliseconds)
+{
+  volatile int i;
+  volatile int j;
+
+  for (i = 0; i < milliseconds; i++)
+    {
+        for (j = 0; j < CONFIG_BOARD_LOOPSPERMSEC; j++)
+          {
+          }
+    }
+}
+
diff --git a/nuttx/arch/avr/src/common/up_modifyreg16.c b/nuttx/arch/avr/src/common/up_modifyreg16.c
new file mode 100644
index 000000000..e06f91f96
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_modifyreg16.c
@@ -0,0 +1,86 @@
+/****************************************************************************
+ * arch/avr/src/common/up_modifyreg16.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+#include <nuttx/arch.h>
+
+#include "up_arch.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: modifyreg16
+ *
+ * Description:
+ *   Atomically modify the specified bits in a memory mapped register
+ *
+ ****************************************************************************/
+
+void modifyreg16(unsigned int addr, uint16_t clearbits, uint16_t setbits)
+{
+  irqstate_t flags;
+  uint16_t   regval;
+
+  flags   = irqsave();
+  regval  = getreg16(addr);
+  regval &= ~clearbits;
+  regval |= setbits;
+  putreg16(regval, addr);
+  irqrestore(flags);
+}
+
diff --git a/nuttx/arch/avr/src/common/up_modifyreg32.c b/nuttx/arch/avr/src/common/up_modifyreg32.c
new file mode 100644
index 000000000..3369abb56
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_modifyreg32.c
@@ -0,0 +1,86 @@
+/****************************************************************************
+ * arch/avr/src/common/up_modifyreg32.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+#include <nuttx/arch.h>
+
+#include "up_arch.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: modifyreg32
+ *
+ * Description:
+ *   Atomically modify the specified bits in a memory mapped register
+ *
+ ****************************************************************************/
+
+void modifyreg32(unsigned int addr, uint32_t clearbits, uint32_t setbits)
+{
+  irqstate_t flags;
+  uint32_t   regval;
+
+  flags   = irqsave();
+  regval  = getreg32(addr);
+  regval &= ~clearbits;
+  regval |= setbits;
+  putreg32(regval, addr);
+  irqrestore(flags);
+}
+
diff --git a/nuttx/arch/avr/src/common/up_modifyreg8.c b/nuttx/arch/avr/src/common/up_modifyreg8.c
new file mode 100644
index 000000000..35537a4ab
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_modifyreg8.c
@@ -0,0 +1,86 @@
+/****************************************************************************
+ * arch/avr/src/common/up_modifyreg8.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+#include <nuttx/arch.h>
+
+#include "up_arch.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: modifyreg8
+ *
+ * Description:
+ *   Atomically modify the specified bits in a memory mapped register
+ *
+ ****************************************************************************/
+
+void modifyreg8(unsigned int addr, uint8_t clearbits, uint8_t setbits)
+{
+  irqstate_t flags;
+  uint8_t    regval;
+
+  flags   = irqsave();
+  regval  = getreg8(addr);
+  regval &= ~clearbits;
+  regval |= setbits;
+  putreg8(regval, addr);
+  irqrestore(flags);
+}
+
diff --git a/nuttx/arch/avr/src/common/up_puts.c b/nuttx/arch/avr/src/common/up_puts.c
new file mode 100644
index 000000000..aa651e294
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_puts.c
@@ -0,0 +1,76 @@
+/****************************************************************************
+ * arch/avr/src/common/up_puts.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/arch.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_puts
+ *
+ * Description:
+ *   This is a low-level helper function used to support debug.
+ *
+ ****************************************************************************/
+
+void up_puts(const char *str)
+{
+  while(*str)
+    {
+      up_putc(*str++);
+    }
+}
+
diff --git a/nuttx/arch/avr/src/common/up_releasestack.c b/nuttx/arch/avr/src/common/up_releasestack.c
new file mode 100644
index 000000000..4c453c590
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_releasestack.c
@@ -0,0 +1,80 @@
+/****************************************************************************
+ *  arch/avr/src/common/up_releasestack.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_release_stack
+ *
+ * Description:
+ *   A task has been stopped. Free all stack
+ *   related resources retained int the defunct TCB.
+ *
+ ****************************************************************************/
+
+void up_release_stack(_TCB *dtcb)
+{
+  if (dtcb->stack_alloc_ptr)
+    {
+      sched_free(dtcb->stack_alloc_ptr);
+      dtcb->stack_alloc_ptr = NULL;
+    }
+
+  dtcb->adj_stack_size = 0;
+}
+
diff --git a/nuttx/arch/avr/src/common/up_udelay.c b/nuttx/arch/avr/src/common/up_udelay.c
new file mode 100644
index 000000000..5bbeed907
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_udelay.c
@@ -0,0 +1,130 @@
+/****************************************************************************
+ *  arch/avr/src/common/up_udelay.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <nuttx/arch.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+#define CONFIG_BOARD_LOOPSPER100USEC ((CONFIG_BOARD_LOOPSPERMSEC+5)/10)
+#define CONFIG_BOARD_LOOPSPER10USEC  ((CONFIG_BOARD_LOOPSPERMSEC+50)/100)
+#define CONFIG_BOARD_LOOPSPERUSEC    ((CONFIG_BOARD_LOOPSPERMSEC+500)/1000)
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_udelay
+ *
+ * Description:
+ *   Delay inline for the requested number of microseconds.  NOTE:  Because
+ *   of all of the setup, several microseconds will be lost before the actual
+ *   timing looop begins.  Thus, the delay will always be a few microseconds
+ *   longer than requested.
+ *
+ *   *** NOT multi-tasking friendly ***
+ *
+ * ASSUMPTIONS:
+ *   The setting CONFIG_BOARD_LOOPSPERMSEC has been calibrated
+ *
+ ****************************************************************************/
+
+void up_udelay(useconds_t microseconds)
+{
+  volatile int i;
+
+  /* We'll do this a little at a time because we expect that the
+   * CONFIG_BOARD_LOOPSPERUSEC is very inaccurate during to truncation in
+   * the divisions of its calculation.  We'll use the largest values that
+   * we can in order to prevent significant error buildup in the loops.
+   */
+
+  while (microseconds > 1000)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPERMSEC; i++)
+        {
+        }
+      microseconds -= 1000;
+    }
+
+  while (microseconds > 100)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPER100USEC; i++)
+        {
+        }
+      microseconds -= 100;
+    }
+
+  while (microseconds > 10)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPER10USEC; i++)
+        {
+        }
+      microseconds -= 10;
+    }
+
+  while (microseconds > 0)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPERUSEC; i++)
+        {
+        }
+      microseconds--;
+    }
+}
+
diff --git a/nuttx/arch/avr/src/common/up_usestack.c b/nuttx/arch/avr/src/common/up_usestack.c
new file mode 100644
index 000000000..b2da00cf2
--- /dev/null
+++ b/nuttx/arch/avr/src/common/up_usestack.c
@@ -0,0 +1,123 @@
+/****************************************************************************
+ * arch/avr/src/common/up_usestack.c
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/arch.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_use_stack
+ *
+ * Description:
+ *   Setup up stack-related information in the TCB
+ *   using pre-allocated stack memory
+ *
+ *   The following TCB fields must be initialized:
+ *   adj_stack_size: Stack size after adjustment for hardware,
+ *     processor, etc.  This value is retained only for debug
+ *     purposes.
+ *   stack_alloc_ptr: Pointer to allocated stack
+ *   adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The
+ *     initial value of the stack pointer.
+ *
+ * Inputs:
+ *   tcb: The TCB of new task
+ *   stack_size:  The allocated stack size.
+ *
+ ****************************************************************************/
+
+int up_use_stack(_TCB *tcb, void *stack, size_t stack_size)
+{
+  size_t top_of_stack;
+  size_t size_of_stack;
+
+  if (tcb->stack_alloc_ptr)
+    {
+      sched_free(tcb->stack_alloc_ptr);
+    }
+
+  /* Save the stack allocation */
+
+  tcb->stack_alloc_ptr = stack;
+
+  /* The AVR32 uses a push-down stack:  the stack grows
+   * toward loweraddresses in memory.  The stack pointer
+   * register, points to the lowest, valid work address
+   * (the "top" of the stack).  Items on the stack are
+   * referenced as positive word offsets from sp.
+   */
+
+  top_of_stack = (uint32_t)tcb->stack_alloc_ptr + stack_size - 4;
+
+  /* The AVR32 stack must be aligned at word (4 byte)
+   * boundaries. If necessary top_of_stack must be rounded
+   * down to the next boundary
+   */
+
+  top_of_stack &= ~3;
+  size_of_stack = top_of_stack - (uint32_t)tcb->stack_alloc_ptr + 4;
+
+  /* Save the adjusted stack values in the _TCB */
+
+  tcb->adj_stack_ptr  = (uint32_t*)top_of_stack;
+  tcb->adj_stack_size = size_of_stack;
+
+  return OK;
+}
+