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| Page date Wed Aug 5 13:48:01 2015 . | Improve this page |
If some parts of the code are platform dependent, test the following preprocessor definitions:
#if defined(__APPLE__)
#if defined(__linux__)
#if defined(__x86_64__)
To check the compiler:
#if defined (__GNUC__)
#if __GNUC__ == 4 && __GNUC_MINOR__ == 7
#if defined(__clang__)
To check the size of the pointer:
#if __SIZEOF_POINTER__ == __SIZEOF_INT__
#elif __SIZEOF_POINTER__ == __SIZEOF_LONG__
#elif __SIZEOF_POINTER__ == __SIZEOF_LONG_LONG__
To check if there are no long long variables:
#if !defined(__SIZEOF_LONG_LONG)
To check if the compiling unit is C++:
#if defined (__cplusplus)
To check if the compiling unit is an assembly file:
#if defined(__ASSEMBLER__)
To check if optimisation is enabled (more than -O0):
#if defined(__OPTIMIZE__)
To check if optimisation for size is enabled (-Os):
#if defined(__OPTIMIZE_SIZE__)
To check if no inlines are enabled:
#if defined(__NO_INLINE__)
To see the GCC defines use:
g++ -dM -E - < /dev/null
clang++ -dM -E - < /dev/null
When compiling Cortex-M applications, GCC 4.8 provides the following built-in definitions.
$ ./arm-none-eabi-gcc -mcpu=cortex-m0 -mthumb -E -dM - < /dev/null | egrep -i 'thumb|arm|cortex' | sort
#define __ARMEL__ 1
#define __ARM_ARCH 6
#define __ARM_ARCH_6M__ 1
#define __ARM_ARCH_ISA_THUMB 1
#define __ARM_ARCH_PROFILE 77
#define __ARM_EABI__ 1
#define __ARM_FP 12
#define __ARM_NEON_FP 4
#define __ARM_PCS 1
#define __ARM_SIZEOF_MINIMAL_ENUM 1
#define __ARM_SIZEOF_WCHAR_T 4
#define __THUMBEL__ 1
#define __THUMB_INTERWORK__ 1
#define __VERSION__ "4.9.3 20150303 (release) [ARM/embedded-4_9-branch revision 221220]"
#define __arm__ 1
#define __thumb__ 1
$ ./arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -E -dM - < /dev/null | egrep -i 'thumb|arm|cortex' | sort
#define __ARMEL__ 1
#define __ARM_32BIT_STATE 1
#define __ARM_ARCH 7
#define __ARM_ARCH_7M__ 1
#define __ARM_ARCH_EXT_IDIV__ 1
#define __ARM_ARCH_ISA_THUMB 2
#define __ARM_ARCH_PROFILE 77
#define __ARM_EABI__ 1
#define __ARM_FEATURE_CLZ 1
#define __ARM_FEATURE_LDREX 7
#define __ARM_FEATURE_QBIT 1
#define __ARM_FEATURE_SAT 1
#define __ARM_FEATURE_UNALIGNED 1
#define __ARM_FP 12
#define __ARM_NEON_FP 4
#define __ARM_PCS 1
#define __ARM_SIZEOF_MINIMAL_ENUM 1
#define __ARM_SIZEOF_WCHAR_T 4
#define __THUMBEL__ 1
#define __THUMB_INTERWORK__ 1
#define __VERSION__ "4.9.3 20150303 (release) [ARM/embedded-4_9-branch revision 221220]"
#define __arm__ 1
#define __thumb2__ 1
#define __thumb__ 1
$ ./arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=soft \
-E -dM - < /dev/null | egrep -i 'thumb|arm|cortex|fp__|version|abi' | sort
#define __ARMEL__ 1
#define __ARM_32BIT_STATE 1
#define __ARM_ARCH 7
#define __ARM_ARCH_7EM__ 1
#define __ARM_ARCH_EXT_IDIV__ 1
#define __ARM_ARCH_ISA_THUMB 2
#define __ARM_ARCH_PROFILE 77
#define __ARM_EABI__ 1
#define __ARM_FEATURE_CLZ 1
#define __ARM_FEATURE_DSP 1
#define __ARM_FEATURE_LDREX 7
#define __ARM_FEATURE_QBIT 1
#define __ARM_FEATURE_SAT 1
#define __ARM_FEATURE_SIMD32 1
#define __ARM_FEATURE_UNALIGNED 1
#define __ARM_FP 12
#define __ARM_NEON_FP 4
#define __ARM_PCS 1
#define __ARM_SIZEOF_MINIMAL_ENUM 1
#define __ARM_SIZEOF_WCHAR_T 4
#define __GXX_ABI_VERSION 1002
#define __SOFTFP__ 1
#define __THUMBEL__ 1
#define __THUMB_INTERWORK__ 1
#define __VERSION__ "4.9.3 20150303 (release) [ARM/embedded-4_9-branch revision 221220]"
#define __VFP_FP__ 1
#define __arm__ 1
#define __thumb2__ 1
#define __thumb__ 1
$ ./arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard \
-mfpu=fpv4-sp-d16 -E -dM - < /dev/null | egrep -i 'thumb|arm|cortex|fp__|version|abi' | sort
#define __ARMEL__ 1
#define __ARM_32BIT_STATE 1
#define __ARM_ARCH 7
#define __ARM_ARCH_7EM__ 1
#define __ARM_ARCH_EXT_IDIV__ 1
#define __ARM_ARCH_ISA_THUMB 2
#define __ARM_ARCH_PROFILE 77
#define __ARM_EABI__ 1
#define __ARM_FEATURE_CLZ 1
#define __ARM_FEATURE_DSP 1
#define __ARM_FEATURE_FMA 1
#define __ARM_FEATURE_LDREX 7
#define __ARM_FEATURE_QBIT 1
#define __ARM_FEATURE_SAT 1
#define __ARM_FEATURE_SIMD32 1
#define __ARM_FEATURE_UNALIGNED 1
#define __ARM_FP 4
#define __ARM_NEON_FP 4
#define __ARM_PCS_VFP 1
#define __ARM_SIZEOF_MINIMAL_ENUM 1
#define __ARM_SIZEOF_WCHAR_T 4
#define __GXX_ABI_VERSION 1002
#define __THUMBEL__ 1
#define __THUMB_INTERWORK__ 1
#define __VERSION__ "4.9.3 20150303 (release) [ARM/embedded-4_9-branch revision 221220]"
#define __VFP_FP__ 1
#define __arm__ 1
#define __thumb2__ 1
#define __thumb__ 1
$ ./arm-none-eabi-gcc -mcpu=cortex-m7 -mthumb -mfloat-abi=soft \
-E -dM - < /dev/null | egrep -i 'thumb|arm|cortex|fp__|version|abi' | sort
#define __ARMEL__ 1
#define __ARM_32BIT_STATE 1
#define __ARM_ARCH 7
#define __ARM_ARCH_7EM__ 1
#define __ARM_ARCH_EXT_IDIV__ 1
#define __ARM_ARCH_ISA_THUMB 2
#define __ARM_ARCH_PROFILE 77
#define __ARM_EABI__ 1
#define __ARM_FEATURE_CLZ 1
#define __ARM_FEATURE_DSP 1
#define __ARM_FEATURE_LDREX 7
#define __ARM_FEATURE_QBIT 1
#define __ARM_FEATURE_SAT 1
#define __ARM_FEATURE_SIMD32 1
#define __ARM_FEATURE_UNALIGNED 1
#define __ARM_FP 12
#define __ARM_NEON_FP 4
#define __ARM_PCS 1
#define __ARM_SIZEOF_MINIMAL_ENUM 1
#define __ARM_SIZEOF_WCHAR_T 4
#define __GXX_ABI_VERSION 1002
#define __SOFTFP__ 1
#define __THUMBEL__ 1
#define __THUMB_INTERWORK__ 1
#define __VERSION__ "4.9.3 20150303 (release) [ARM/embedded-4_9-branch revision 221220]"
#define __VFP_FP__ 1
#define __arm__ 1
#define __thumb2__ 1
#define __thumb__ 1
To check if -ffreestanding was defined, you can use the following:
#define __STDC_HOSTED__ 0
By default, i.e. with -fhosted defined, the value is 1.
To check if a C++ program is compiled with -fexceptions, use:
#define __EXCEPTIONS 1
#define __CHAR_UNSIGNED__ 1
#define __LP64__ 1
When compiling third party sources, it might be necessary to temporarily disable some warnings:
// [ILG]
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wundef"
#pragma GCC diagnostic ignored "-Wsign-conversion"
// [ILG]
#pragma GCC diagnostic pop
// [ILG]
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wundef"
// [ILG]
#pragma clang diagnostic pop
