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Diffstat (limited to 'docs/source/arm-gcc.rst')
| -rw-r--r-- | docs/source/arm-gcc.rst | 53 |
1 files changed, 34 insertions, 19 deletions
diff --git a/docs/source/arm-gcc.rst b/docs/source/arm-gcc.rst index ef745f5..e97bb2f 100644 --- a/docs/source/arm-gcc.rst +++ b/docs/source/arm-gcc.rst @@ -4,12 +4,11 @@ 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/>`_. +This document provides notes on using of ``arm-none-eabi-gcc``, the +`CodeSourcery <http://www.codesourcery.com/>`_ version of the GNU `GCC +<http://gcc.gnu.org/>`_ compilers used for the Maple boards. It is +not intended as a reference manual for GCC; such manuals are available +`elsewhere <http://gcc.gnu.org/>`_. Obtaining ``arm-none-eabi-gcc`` ------------------------------- @@ -17,21 +16,24 @@ 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. +Users who wish to use ``arm-none-eabi-gcc`` directly, along with a +standard Unix Make-based toolchain, should read the +:ref:`unix-toolchain`, 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. +LeafLabs maintains `mirrors +<http://static.leaflabs.com/pub/codesourcery/>`_ for some of the more +recent versions of the compiler, 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. +the :ref:`Maple IDE <ide>` and the default Makefile provided with the +:ref:`Unix toolchain <unix-toolchain>`. The information in this +section is subject to change between :ref:`libmaple <libmaple>` +releases. .. highlight:: sh @@ -40,7 +42,8 @@ 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:: +In addition to those flags just given for the C compiler, the +following flags are among those passed to the C++ compiler:: -fno-rtti -fno-exceptions -Wall @@ -52,6 +55,15 @@ The following flags are among those passed to the assembler:: .. _arm-gcc-avr-gcc: +Using the C Standard Library +---------------------------- + +By default (under both the :ref:`Maple IDE <ide>` and the :ref:`Unix +toolchain <unix-toolchain>`), ``arm-none-eabi-gcc`` is configured to +link against `newlib <http://sourceware.org/newlib/>`_, a C standard +library intended for use with embedded applications. You are free to +include of any of its headers. + Switching from AVR-GCC ---------------------- @@ -63,8 +75,11 @@ including Arduino) for use on the Maple. .. _arm-gcc-attribute-flash: - 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:: + with libmaple to store a variable in Flash (instead of RAM) by using + the libmaple macro ``__FLASH__``, like so:: - uint32 arr[] __attribute__((section (".USER_FLASH"))) = {...}; + uint32 array[] __FLASH__ = {0, 1, 2}; + Be aware, however, that if you do that, you can only store values + which are compile-time constants, and that if you attempt to change + a variable stored in Flash, your program will crash. |