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| author | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2014-04-07 14:50:24 +0200 |
|---|---|---|
| committer | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2014-04-07 14:51:31 +0200 |
| commit | 57740ce8a1e2370f7fc29c8bcf634e480f920e2b (patch) | |
| tree | f29e367cc1991b4b12632cb683d59dd8f7d2d1f8 | |
| parent | Disable per task variables when SMP is enabled (diff) | |
| download | rtems-57740ce8a1e2370f7fc29c8bcf634e480f920e2b.tar.bz2 | |
score: Clarify CPU port alignment requirements
| -rw-r--r-- | cpukit/score/cpu/no_cpu/rtems/score/cpu.h | 16 | ||||
| -rw-r--r-- | cpukit/score/src/percpuasm.c | 35 |
2 files changed, 42 insertions, 9 deletions
diff --git a/cpukit/score/cpu/no_cpu/rtems/score/cpu.h b/cpukit/score/cpu/no_cpu/rtems/score/cpu.h index 0b6c4dac72..c864164667 100644 --- a/cpukit/score/cpu/no_cpu/rtems/score/cpu.h +++ b/cpukit/score/cpu/no_cpu/rtems/score/cpu.h @@ -733,7 +733,10 @@ SCORE_EXTERN Context_Control_fp _CPU_Null_fp_context; /** * CPU's worst alignment requirement for data types on a byte boundary. This - * alignment does not take into account the requirements for the stack. + * alignment does not take into account the requirements for the stack. It + * must be a power of two greater than or equal to two. The power of two + * requirement makes it possible to align values easily using simple bit + * operations. * * Port Specific Information: * @@ -749,12 +752,11 @@ SCORE_EXTERN Context_Control_fp _CPU_Null_fp_context; * @ref CPU_ALIGNMENT. If the @ref CPU_ALIGNMENT is strict enough for * the heap, then this should be set to @ref CPU_ALIGNMENT. * - * NOTE: This does not have to be a power of 2 although it should be - * a multiple of 2 greater than or equal to 2. The requirement - * to be a multiple of 2 is because the heap uses the least - * significant field of the front and back flags to indicate - * that a block is in use or free. So you do not want any odd - * length blocks really putting length data in that bit. + * NOTE: It must be a power of two greater than or equal to two. The + * requirement to be a multiple of two is because the heap uses the + * least significant field of the front and back flags to indicate that + * a block is in use or free. So you do not want any odd length blocks + * really putting length data in that bit. * * On byte oriented architectures, @ref CPU_HEAP_ALIGNMENT normally will * have to be greater or equal to than @ref CPU_ALIGNMENT to ensure that diff --git a/cpukit/score/src/percpuasm.c b/cpukit/score/src/percpuasm.c index d6bf756cf7..d422a0deb6 100644 --- a/cpukit/score/src/percpuasm.c +++ b/cpukit/score/src/percpuasm.c @@ -1,8 +1,8 @@ /* - * Copyright (c) 2012 embedded brains GmbH. All rights reserved. + * Copyright (c) 2012-2014 embedded brains GmbH. All rights reserved. * * embedded brains GmbH - * Obere Lagerstr. 30 + * Dornierstr. 4 * 82178 Puchheim * Germany * <rtems@embedded-brains.de> @@ -21,6 +21,37 @@ #define _RTEMS_PERCPU_DEFINE_OFFSETS #include <rtems/score/percpu.h> +/* + * In case a CPU port needs another alignment, then add this here and make sure + * it is a power of two greater than or equal to two. + */ +RTEMS_STATIC_ASSERT( + CPU_ALIGNMENT == 2 + || CPU_ALIGNMENT == 4 + || CPU_ALIGNMENT == 8 + || CPU_ALIGNMENT == 16 + || CPU_ALIGNMENT == 32, + CPU_ALIGNMENT +); + +/* + * In case a CPU port needs another heap alignment, then add this here and make + * sure it is a power of two greater than or equal to two. + */ +RTEMS_STATIC_ASSERT( + CPU_HEAP_ALIGNMENT == 2 + || CPU_HEAP_ALIGNMENT == 4 + || CPU_HEAP_ALIGNMENT == 8 + || CPU_HEAP_ALIGNMENT == 16 + || CPU_HEAP_ALIGNMENT == 32, + CPU_HEAP_ALIGNMENT_0 +); + +RTEMS_STATIC_ASSERT( + CPU_HEAP_ALIGNMENT >= CPU_ALIGNMENT, + CPU_HEAP_ALIGNMENT_1 +); + RTEMS_STATIC_ASSERT( sizeof(void *) == CPU_SIZEOF_POINTER, CPU_SIZEOF_POINTER |