Merge branch 'master' into debug-serialusb.

Chose debug-serialusb version in cases of conflict.

Conflicts:
	libmaple/usb/usb_callbacks.c

1 files changed, 64 insertions, 7 deletions

diff --git a/docs/source/arm-gcc.rst b/docs/source/arm-gcc.rst
index 21379db..ef745f5 100644
--- a/docs/source/arm-gcc.rst
+++ b/docs/source/arm-gcc.rst
@@ -1,13 +1,70 @@
 
 .. _arm-gcc:
-.. _arm-gcc-attribute-flash:
 
-============
- GCC on ARM
-============
+GCC for Maple
+=============
+
+This document provides notes on the current usage of
+``arm-none-eabi-gcc``, the `CodeSourcery <http://codesourcery.com>`_
+version of the GNU `GCC <http://gcc.gnu.org/>`_ compilers used to
+compile programs for the Maple.  It is not intended as a reference
+manual for GCC; such manuals are available `elsewhere
+<http://gcc.gnu.org/>`_.
+
+Obtaining ``arm-none-eabi-gcc``
+-------------------------------
+
+Recent versions of ``arm-none-eabi-gcc`` and associated tools are
+included with the :ref:`Maple IDE <ide>`.
+
+Users who wish to use ``arm-none-eabi-gcc`` in concert with a standard
+Unix toolchain are referred to our :ref:`unix-toolchain` reference,
+which describes how to set up such an environment.
+
+LeafLabs mirrors some of the more recent versions of the compiler
+under http://static.leaflabs.com/pub/codesourcery/\ , including
+versions for OS X, win32, and 32-bit Linux.
+
+Compiler Flags Used by libmaple
+-------------------------------
+
+This section documents the flags passed to ``arm-none-eabi-gcc`` by
+the :ref:`Maple IDE <ide>` and the default Makefile provided with
+:ref:`libmaple <unix-toolchain>`.  The information in this section is
+subject to change without notice.
+
+.. highlight:: sh
+
+The following flags are among those passed to the C compiler::
+
+    -Os -g -mcpu=cortex-m3 -mthumb -march=armv7-m -nostdlib
+    -ffunction-sections -fdata-sections -Wl,--gc-sections
+
+The following flags are among those passed to the C++ compiler::
+
+    -fno-rtti -fno-exceptions -Wall
+
+The following flags are among those passed to the assembler::
+
+    -mcpu=cortex-m3 -march=armv7-m -mthumb
+
+.. highlight:: cpp
+
+.. _arm-gcc-avr-gcc:
+
+Switching from AVR-GCC
+----------------------
+
+This section, which is expected to grow over time, describes
+techniques for porting code which uses AVR-GCC features (AVR-GCC is
+the compiler used by many Atmel AVR-based microcontroller boards,
+including Arduino) for use on the Maple.
+
+.. _arm-gcc-attribute-flash:
 
-Stub.
+- Replacing ``PROGMEM``: You can direct the linker script provided
+  with libmaple to store a variable in flash by using
+  ``__attribute__((section (".USER_FLASH")))``, like so::
 
-Include special things, differences with AVR-GCC, using
-``__attribute__`` to stick things in flash, etc.
+      uint32 arr[] __attribute__((section (".USER_FLASH"))) = {...};