NET: Add generic I/O buffering logic

11 files changed, 1073 insertions, 0 deletions

diff --git a/nuttx/net/iob/Kconfig b/nuttx/net/iob/Kconfig
new file mode 100644
index 000000000..0a5c8522a
--- /dev/null
+++ b/nuttx/net/iob/Kconfig
@@ -0,0 +1,31 @@
+#
+# For a description of the syntax of this configuration file,
+# see misc/tools/kconfig-language.txt.
+#
+
+config NET_IOB
+	bool "Network I/O buffer support"
+	default n
+	---help---
+		This setting will build the networking I/O buffer (IOB) support
+		library.
+
+if NET_IOB
+
+config IOB_NBUFFERS
+	int "Number of pre-allocated network I/O buffers"
+	default 16
+	---help---
+		Each packet is represented by a series of small I/O buffers in a
+		chain.  This setting determines the number of preallocated I/O
+		buffers available for packet data.
+
+config IOB_BUFSIZE
+	int "Payload size of one network I/O buffer"
+	default 256
+	---help---
+		Each packet is represented by a series of small I/O buffers in a
+		chain.  This setting determines the data payload each preallocated
+		I/O buffer.
+
+endif # NET_IOB
diff --git a/nuttx/net/iob/Make.defs b/nuttx/net/iob/Make.defs
new file mode 100644
index 000000000..6783e597b
--- /dev/null
+++ b/nuttx/net/iob/Make.defs
@@ -0,0 +1,52 @@
+############################################################################
+# net/iob/Make.defs
+#
+#   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# 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.
+#
+############################################################################
+
+NET_ASRCS =
+NET_CSRCS =
+
+ifeq ($(CONFIG_NET_IOB),y)
+
+# Include IOB src files
+
+NET_CSRCS += iob_alloc.c iob_concat.c iob_copyout.c iob_free.c iob_freeq.c
+NET_CSRCS += iob_initialize.c iob_trimhead.c iob_trimtail.c
+
+# Include iob build support
+
+DEPPATH += --dep-path iob
+VPATH += :iob
+CFLAGS += ${shell $(INCDIR) $(INCDIROPT) "$(CC)" $(TOPDIR)$(DELIM)net$(DELIM)iob}
+
+endif
diff --git a/nuttx/net/iob/iob.h b/nuttx/net/iob/iob.h
new file mode 100644
index 000000000..1a6fe540c
--- /dev/null
+++ b/nuttx/net/iob/iob.h
@@ -0,0 +1,78 @@
+/****************************************************************************
+ * net/iob/iob.h
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 __NET_IOB_IOB_H
+#define __NET_IOB_IOB_H 1
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/* This is a pool of pre-allocated I/O buffers */
+
+extern struct iob_s g_iob_pool[CONFIG_IOB_NBUFFERS];
+
+/* A list of all free, unallocated I/O buffers */
+
+extern sq_queue_t g_iob_freelist;
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+
+#endif /* __NET_IOB_IOB_H */
diff --git a/nuttx/net/iob/iob_alloc.c b/nuttx/net/iob/iob_alloc.c
new file mode 100644
index 000000000..c2c060d84
--- /dev/null
+++ b/nuttx/net/iob/iob_alloc.c
@@ -0,0 +1,79 @@
+/****************************************************************************
+ * net/iob/iob_alloc.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_alloc
+ *
+ * Description:
+ *   Allocate an I/O buffer by take the buffer at the head of the free list.
+ *
+ ****************************************************************************/
+
+FAR struct iob_s *iob_alloc(void)
+{
+  return (FAR struct iob_s *)sq_remfirst(&g_iob_freelist);
+}
diff --git a/nuttx/net/iob/iob_concat.c b/nuttx/net/iob/iob_concat.c
new file mode 100644
index 000000000..d7b03e1fc
--- /dev/null
+++ b/nuttx/net/iob/iob_concat.c
@@ -0,0 +1,158 @@
+/****************************************************************************
+ * net/iob/iob_concat.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <string.h>
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_concat
+ *
+ * Description:
+ *   Concatenate iob_s chain iob2 to iob1.
+ *
+ ****************************************************************************/
+
+void iob_concat(FAR struct iob_s *iob1, FAR struct iob_s *iob2)
+{
+  unsigned int offset2;
+  unsigned int ncopy;
+  unsigned int navail;
+
+  /* Find the last buffer in the iob1 buffer chain */
+ 
+  while (iob1->io_link.flink)
+    {
+      iob1 = (FAR struct iob_s *)iob1->io_link.flink;
+    }
+
+  /* Then add data to the end of iob1 */
+
+  offset2 = 0;
+  while (iob2)
+    {
+      /* Is the iob1 tail buffer full? */
+
+      if (iob1->io_len >= CONFIG_IOB_BUFSIZE)
+        {
+          /* Yes.. Just connect the chains */
+
+          iob1->io_link.flink = iob2->io_link.flink;
+
+          /* Has the data offset in iob2? */
+
+          if (offset2 > 0)
+            {
+              /* Yes, move the data down and adjust the size */
+
+              iob2->io_len -= offset2;
+              memcpy(iob2->io_data, &iob2->io_data[offset2], iob2->io_len);
+
+              /* Set up to continue packing, but now into iob2 */
+
+              iob1 = iob2;
+              iob2 = (FAR struct iob_s *)iob2->io_link.flink;
+
+              iob1->io_link.flink = NULL;
+              offset2 = 0;
+            }
+          else
+            {
+              /* Otherwise, we are done */
+
+              return;
+            }
+        }
+
+      /* How many bytes can we copy from the source (iob2) */
+
+      ncopy = iob2->io_len - offset2;
+
+      /* Limit the size of the copy to the amount of free space in iob1 */
+
+      navail = CONFIG_IOB_BUFSIZE - iob1->io_len;
+      if (ncopy > navail)
+        {
+          ncopy = navail;
+        }
+
+      /* Copy the data from iob2 into iob1 */
+
+      memcpy(iob1->io_data + iob1->io_len, iob2->io_data, ncopy);
+      iob1->io_len += ncopy;
+      offset2 += ncopy;
+
+      /* Have we consumed all of the data in the iob2 entry? */
+
+      if (offset2 >= iob2->io_len)
+        {
+          /* Yes.. free the iob2 entry and start processing the next I/O
+           * buffer in the iob2 chain.
+           */
+
+          iob2 = iob_free(iob2);
+          offset2 = 0;
+        }
+    }
+}
diff --git a/nuttx/net/iob/iob_copyout.c b/nuttx/net/iob/iob_copyout.c
new file mode 100644
index 000000000..5997c7f97
--- /dev/null
+++ b/nuttx/net/iob/iob_copyout.c
@@ -0,0 +1,129 @@
+/****************************************************************************
+ * net/iob/iob_copyout.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <string.h>
+#include <assert.h>
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifndef MIN
+#  define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_copyout
+ *
+ * Description:
+ *  Copy data 'len' bytes of data into the user buffer starting at 'offset'
+ *  in the I/O buffer.
+ *
+ ****************************************************************************/
+
+void iob_copyout(FAR uint8_t *dest, FAR const struct iob_s *iob,
+                 unsigned int len, unsigned int offset)
+{
+  FAR const uint8_t *src;
+  unsigned int ncopy;
+  unsigned int avail;
+
+  /* Skip to the I/O buffer containing the offset */
+
+  while (offset >= iob->io_len)
+    {
+      offset -= iob->io_len;
+      iob     = (FAR struct iob_s *)iob->io_link.flink;
+    }
+
+  /* Then loop until all of the I/O data is copied to the user buffer */
+
+  while (len > 0)
+    {
+      ASSERT(iob);
+
+      /* Get the source I/O buffer offset address and the amount of data
+       * available from that address.
+       */
+
+      src   = &iob->io_data[offset];
+      avail = iob->io_len - offset;
+
+      /* Copy the whole I/O buffer in to the user buffer */
+
+      ncopy = MIN(avail, len);
+      memcpy(dest, src, ncopy);
+
+      /* Adjust the total length of the copy and the destination address in
+       * the user buffer.
+       */
+
+      len  -= ncopy;
+      dest += ncopy;
+
+      /* Skip to the next I/O buffer in the chain */
+
+      iob = (FAR struct iob_s *)iob->io_link.flink;
+      offset = 0;
+    }
+}
diff --git a/nuttx/net/iob/iob_free.c b/nuttx/net/iob/iob_free.c
new file mode 100644
index 000000000..273f4b5a0
--- /dev/null
+++ b/nuttx/net/iob/iob_free.c
@@ -0,0 +1,83 @@
+/****************************************************************************
+ * net/iob/iob_free.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_free
+ *
+ * Description:
+ *   Free the I/O buffer at the head of a buffer chain returning it to the
+ *   free list.  The link to  the next I/O buffer in the chain is return.
+ *
+ ****************************************************************************/
+
+FAR struct iob_s *iob_free(FAR struct iob_s *iob)
+{
+  sq_entry_t *next = iob->io_link.flink;
+
+  sq_addlast(&iob->io_link, &g_iob_freelist);
+  return (FAR struct iob_s *)next;
+}
diff --git a/nuttx/net/iob/iob_freeq.c b/nuttx/net/iob/iob_freeq.c
new file mode 100644
index 000000000..fa9cce8ab
--- /dev/null
+++ b/nuttx/net/iob/iob_freeq.c
@@ -0,0 +1,96 @@
+/****************************************************************************
+ * net/iob/iob_freeq.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_freeq
+ *
+ * Description:
+ *   Free an entire buffer chain
+ *
+ ****************************************************************************/
+
+void iob_freeq(FAR sq_queue_t *q)
+{
+  /* If the free list is empty, then just move the entry queue to the the
+   * free list.  Otherwise, append the list to the end of the free list.
+   */
+
+  if (g_iob_freelist.tail)
+    {
+      g_iob_freelist.tail->flink = q->head;
+    }
+  else
+    {
+      g_iob_freelist.head = q->head;
+    }
+
+  /* In either case, the tail of the queue is the tail of queue becomes the
+   * tail of the free list.
+   */
+
+  g_iob_freelist.tail = q->tail;
+}
diff --git a/nuttx/net/iob/iob_initialize.c b/nuttx/net/iob/iob_initialize.c
new file mode 100644
index 000000000..c5f72c397
--- /dev/null
+++ b/nuttx/net/iob/iob_initialize.c
@@ -0,0 +1,103 @@
+/****************************************************************************
+ * net/iob/iob_initialize.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* This is a pool of pre-allocated I/O buffers */
+
+struct iob_s g_iob_pool[CONFIG_IOB_NBUFFERS];
+
+/* A list of all free, unallocated I/O buffers */
+
+sq_queue_t g_iob_freelist;
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_initialize
+ *
+ * Description:
+ *   Set up the I/O buffers for normal operations.
+ *
+ ****************************************************************************/
+
+void iob_initialize(void)
+{
+  static bool initialized = false;
+  int i;
+
+  /* Perform one-time initialization */
+
+  if (!initialized)
+    {
+      /* Add each I/O buffer to the free list */
+
+      for (i = 0; i < CONFIG_IOB_NBUFFERS; i++)
+        {
+          sq_addlast(&g_iob_pool[i].io_link, &g_iob_freelist);
+        }
+
+      initialized = true;
+    }
+}
diff --git a/nuttx/net/iob/iob_trimhead.c b/nuttx/net/iob/iob_trimhead.c
new file mode 100644
index 000000000..ef6e1c2f6
--- /dev/null
+++ b/nuttx/net/iob/iob_trimhead.c
@@ -0,0 +1,113 @@
+/****************************************************************************
+ * net/iob/iob_trimhead.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <string.h>
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_trimhead
+ *
+ * Description:
+ *   Remove bytes from the beginning of an I/O chain
+ *
+ ****************************************************************************/
+
+void iob_trimhead(FAR struct iob_s *iob, unsigned int trimlen)
+{
+  FAR struct iob_s *entry;
+  unsigned int len;
+
+  if (iob && trimlen > 0)
+    {
+      entry = iob;
+      len   = trimlen;
+
+      /* Trim from the head of the I/IO buffer chain */
+
+      while (entry != NULL && len > 0)
+        {
+          /* Do we trim this entire I/O buffer away? */
+
+          if (entry->io_len <= len)
+            {
+              /* Yes.. just set is length to zero and skip to the next */
+
+              len -= entry->io_len;
+              entry->io_len = 0;
+              entry = (FAR struct iob_s *)entry->io_link.flink;
+            }
+          else
+            {
+              /* No, then just take what we need from this I/O buffer and
+               * stop the trim.
+               */
+
+              entry->io_len -= len;
+              memcpy(entry->io_data, &entry->io_data[len], entry->io_len);
+              len = 0;
+            }
+        }
+    }
+}
diff --git a/nuttx/net/iob/iob_trimtail.c b/nuttx/net/iob/iob_trimtail.c
new file mode 100644
index 000000000..030042be9
--- /dev/null
+++ b/nuttx/net/iob/iob_trimtail.c
@@ -0,0 +1,151 @@
+/****************************************************************************
+ * net/iob/iob_trimtail.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <string.h>
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_trimtail
+ *
+ * Description:
+ *   Remove bytes from the end of an I/O chain
+ *
+ ****************************************************************************/
+
+void iob_trimtail(FAR struct iob_s *iob, unsigned int trimlen)
+{
+  FAR struct iob_s *entry;
+  FAR struct iob_s *penultimate;
+  FAR struct iob_s *last;
+  unsigned int iosize;
+  int len;
+
+  if (iob && trimlen > 0)
+    {
+      len = trimlen;
+
+      /* Loop until complete the trim */
+
+      while (len > 0)
+        {
+          /* Calculate the total length of the data in the I/O buffer
+           * chain and find the last entry in the chain.
+           */
+
+          penultimate = NULL;
+          last = NULL;
+          iosize = 0;
+
+          for (entry = iob;
+               entry;
+               entry = (FAR struct iob_s *)entry->io_link.flink)
+            {
+              /* Accumulate the total size of all buffers in the list */
+
+              iosize += entry->io_len;
+
+              /* Remember the last and the next to the last in the chain */
+
+              penultimate = last;
+              last = entry;
+            }
+
+          /* Trim from the last entry in the chain.  Do we trim this entire
+           * I/O buffer away?
+           */
+
+          if (last->io_len <= len)
+            {
+              /* Yes.. just set is length to zero and skip to the next */
+
+              len -= last->io_len;
+              last->io_len = 0;
+
+              /* There should be a buffer before this one */
+
+              if (!penultimate)
+                {
+                  return;
+                }
+
+              /* Free the last, empty buffer in the list */
+
+              iob_free(last);
+              penultimate->io_link.flink = NULL;
+            }
+               
+          else
+            {
+              /* No, then just take what we need from this I/O buffer and
+               * stop the trim.
+               */
+
+              last->io_len -= len;
+              memcpy(last->io_data, &last->io_data[len], last->io_len);
+              len = 0;
+            }
+        }
+    }
+}