NuttX RTOS

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3

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+Architecture-Specific Code
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The file include/nuttx/arch.h identifies all of the APIs that must
+be provided by the architecture specific logic.  (It also includes
+arch/<arch-name>/arch.h as described below).
+
+Directory Structure
+^^^^^^^^^^^^^^^^^^^
+
+Thie arch directory contains architecture specific logic.  Each aructure
+provide a a subdirectory <arch-name>under arch/ with the folling characteristics:
+
+
+	<arch-name>
+	|-- Make.defs
+	|-- defconfig
+	|-- setenv.sh
+	|-- include
+	|   |-- arch.h
+	|   |-- irq.h
+	|   `-- types.h
+	`-- src
+	    |-- Makefile
+	    `-- (architecture-specific source files)
+
+Summary of Files
+^^^^^^^^^^^^^^^^
+
+Make.defs -- This makefile fragment provides architecture and
+  tool-specific build options.  It will be included by all other
+  makefiles in the build (once it is installed).  This make fragment
+  should define:
+
+	Tools: CC, LD, AR, NM, OBJCOPY, OBJDUMP
+	Tool options: CFLAGS, LDFLAGS
+
+  When this makefile fragment runs, it will be passed TOPDIR which
+  is the path to the root directory of the build.  This makefile
+  fragment may include ${TOPDIR}/.config to perform configuration
+  specific settings.  For example, the CFLAGS will most likely be
+  different if CONFIG_DEBUG=y.
+
+defconfig -- This is a configuration file similar to the Linux
+  configuration file.  In contains varialble/value pairs like:
+
+	CONFIG_VARIABLE=value
+
+  This configuration file will be used at build time:
+
+    (1) as a makefile fragment included in other makefiles, and
+    (2) to generate include/nuttx/config.h which is included by
+        most C files in the system.
+
+  The following variables are recognized by the build (you may
+  also include architecture-specific settings).
+
+	Architecture selection:
+
+		CONFIG_ARCH - identifies the arch subdirectory
+		CONFIG_ARCH_name - for use in C code
+
+	General OS setup
+
+		CONFIG_EXAMPLE - identifies the subdirectgory in examples
+		  that will be used in the build
+		CONFIG_DEBUG - enables built-in debug options
+		CONFIG_DEBUG_VERBOSE - enables verbose debug output
+		CONFIG_HAVE_LOWPUTC - architecture supports low-level, boot
+		  time console output
+		CONFIG_RR_INTERVAL - The round robin timeslice will be set
+		  this number of milliseconds;  Round robin scheduling can
+		  be disabled by setting this value to zero.
+		CONFIG_SCHED_INSTRUMENTATION - enables instrumentation in 
+		  scheduler to monitor system performance
+		CONFIG_TASK_NAME_SIZE - Spcifies that maximum size of a
+		  task name to save in the TCB.  Useful if scheduler
+		  instrumentation is selected.  Set to zero to disable.
+		CONFIG_START_YEAR, CONFIG_START_MONTH, CONFIG_START_DAY -
+		  Used to initialize the internal time logic.
+		CONFIG_JULIAN_TIME - Enables Julian time conversions
+		CONFIG_DEV_CONSOLE - Set if architecture-specific logic
+		  provides /dev/console.  Enables stdout, stderr, stdin.
+
+	Allow for artchitecture optimized implementations
+
+		The architecture can provide optimized versions of the
+		following to improve sysem performance
+
+		CONFIG_ARCH_MEMCPY, CONFIG_ARCH_MEMCMP, CONFIG_ARCH_MEMMOVE
+		CONFIG_ARCH_MEMSET, CONFIG_ARCH_STRCMP, CONFIG_ARCH_STRCPY
+		CONFIG_ARCH_STRNCPY, CONFIG_ARCH_STRLEN, CONFIG_ARCH_BZERO
+		CONFIG_ARCH_KMALLOC, CONFIG_ARCH_KZMALLOC, CONFIG_ARCH_KFREE
+
+	General Compile environment setup
+
+		CONFIG_HAVE_LONG_LONG - enable if your architecture supports
+		  long long types and if you plan to use them
+
+	Sizes of configurable things (0 disables)
+
+		CONFIG_NPTHREAD_KEYS - The number of items of thread-
+		  specific data that can be retained
+		CONFIG_NFILE_DESCRIPTORS - The maximum number of file
+		  descriptors (one for each open)
+		CONFIG_NFILE_STREAMS - The maximum number of streams that
+		  can be fopen'ed
+		CONFIG_STDIO_BUFFER_SIZE - Size of the buffer to allocate
+		  on fopen. (Only if CONFIG_NFILE_STREAMS > 0)
+		CONFIG_NUNGET_CHARS - Number of characters that can be
+		  buffered by ungetc() (Only if CONFIG_NFILE_STREAMS > 0)
+		CONFIG_PREALLOC_MQ_MSGS - The number of pre-allocated message
+		  structures.  The system manages a pool of preallocated
+		  message structures to minimize dynamic allocations
+		CONFIG_MQ_MAXMSGSIZE - Message structures are allocated with
+		  a fixed payload size given by this settin (does not include
+		  other message structure overhead.
+		CONFIG_PREALLOC_WDOGS - The number of pre-allocated watchdog
+		  structures.  The system manages a pool of preallocated
+		  watchdog structures to minimize dynamic allocations
+
+	Stack and heap information
+
+		CONFIG_BOOT_FROM_FLASH - Some configurations support XIP
+		  operation from FLASH.
+		CONFIG_STACK_POINTER - The initial stack pointer
+		CONFIG_PROC_STACK_SIZE - The size of the initial stack
+		CONFIG_PTHREAD_STACK_MIN - Minimum pthread stack size
+		CONFIG_PTHREAD_STACK_DEFAULT - Default pthread stack size
+		CONFIG_HEAP_BASE - The beginning of the heap
+		CONFIG_HEAP_SIZE - The size of the heap
+
+setenv.sh -- This is a script that you can include that will be installed at
+  the toplevel of the directory structure and can be sourced to set any
+  necessary environment variables.
+
+include/arch.h
+  This is a hook for any architecture specific definitions that may
+  be needed by the system.  It is included by include/nuttx/arch.h
+
+include/types.h
+  This provides architecture/toolchain-specific definitions for
+  standard types.  This file should typedef:
+
+  sbyte, ubyte, uint8, boolean, sint16, uint16, sint32, uint32, sint64, uint64
+
+  This file will be included by include/sys/types.h and be made
+  available to all files.
+
+include/irq.h
+  This file needs to define some architecture specific functions (usually
+  inline) and structure.  These include:
+
+  - struct xcptcontext.  This structures represents the saved context
+    of a thread.
+
+  - static inline uint32 irqsave(void) -- Used to disable
+    all interrupts.
+
+  - static inline void irqrestore(uint32 flags) -- Used to
+    restore interrupts enables to the same state as before irqsave
+    was called.
+
+  This file must also define NR_IRQS, the total number of IRQs supported
+  by the board.
+
+src/Makefile
+  This makefile will be executed to build the targets src/libup.a and
+  src/up_head.o.  The up_head.o file holds the entry point into the system
+  (power-on reset entry point, for example).  It will be used in
+  the final link with libup.a and other system archives to generate the
+  final executable.
+
+Configuring NuttX
+^^^^^^^^^^^^^^^^^
+
+Configuring NuttX requires only copying
+
+  arch/<arch-name>/Make.def to ${TOPDIR}/Make.defs
+  arch/<arch-name>/setenv.sh to ${TOPDIR}/setenv.sh
+  arch/<arch-name>/defconfig to ${TOPDIR}/.config
+
+There is a script that automates these steps.  The following steps will
+accomplish the same configuration:
+
+  cd tools
+  ./configure.sh <arch-name>
+
+