93 lines
3.3 KiB
C
93 lines
3.3 KiB
C
/*
|
|
* Copyright (c) 2010, 2012, 2014 Wind River Systems, Inc.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
* @brief Macros to generate structure member offset definitions
|
|
*
|
|
* This header contains macros to allow a kernel implementation to generate
|
|
* absolute symbols whose values represents the member offsets for various
|
|
* kernel structures. These absolute symbols are typically utilized by
|
|
* assembly source files rather than hardcoding the values in some local header
|
|
* file.
|
|
*
|
|
* WARNING: Absolute symbols can potentially be utilized by external tools --
|
|
* for example, to locate a specific field within a data structure.
|
|
* Consequently, changes made to such symbols may require modifications to the
|
|
* associated tool(s). Typically, relocating a member of a structure merely
|
|
* requires that a tool be rebuilt; however, moving a member to another
|
|
* structure (or to a new sub-structure within an existing structure) may
|
|
* require that the tool itself be modified. Likewise, deleting, renaming, or
|
|
* changing the meaning of an absolute symbol may require modifications to a
|
|
* tool.
|
|
*
|
|
* The macro "GEN_OFFSET_SYM(structure, member)" is used to generate a single
|
|
* absolute symbol. The absolute symbol will appear in the object module
|
|
* generated from the source file that utilizes the GEN_OFFSET_SYM() macro.
|
|
* Absolute symbols representing a structure member offset have the following
|
|
* form:
|
|
*
|
|
* __<structure>_<member>_OFFSET
|
|
*
|
|
* This header also defines the GEN_ABSOLUTE_SYM macro to simply define an
|
|
* absolute symbol, irrespective of whether the value represents a structure
|
|
* or offset.
|
|
*
|
|
* The following sample file illustrates the usage of the macros available
|
|
* in this file:
|
|
*
|
|
* <START of sample source file: offsets.c>
|
|
*
|
|
* #include <gen_offset.h>
|
|
* /@ include struct definitions for which offsets symbols are to be
|
|
* generated @/
|
|
*
|
|
* #include <kernel_structs.h>
|
|
* GEN_ABS_SYM_BEGIN (_OffsetAbsSyms) /@ the name parameter is arbitrary @/
|
|
* /@ _kernel_t structure member offsets @/
|
|
*
|
|
* GEN_OFFSET_SYM (_kernel_t, nested);
|
|
* GEN_OFFSET_SYM (_kernel_t, irq_stack);
|
|
* GEN_OFFSET_SYM (_kernel_t, current);
|
|
* GEN_OFFSET_SYM (_kernel_t, idle);
|
|
*
|
|
* GEN_ABSOLUTE_SYM (___kernel_t_SIZEOF, sizeof(_kernel_t));
|
|
*
|
|
* GEN_ABS_SYM_END
|
|
* <END of sample source file: offsets.c>
|
|
*
|
|
* Compiling the sample offsets.c results in the following symbols in offsets.o:
|
|
*
|
|
* $ nm offsets.o
|
|
* 00000000 A ___kernel_t_nested_OFFSET
|
|
* 00000004 A ___kernel_t_irq_stack_OFFSET
|
|
* 00000008 A ___kernel_t_current_OFFSET
|
|
* 0000000c A ___kernel_t_idle_OFFSET
|
|
*/
|
|
|
|
#ifndef _GEN_OFFSET_H
|
|
#define _GEN_OFFSET_H
|
|
|
|
#include <toolchain.h>
|
|
#include <stddef.h>
|
|
|
|
/* definition of the GEN_OFFSET_SYM() macros is toolchain independent */
|
|
|
|
#define GEN_OFFSET_SYM(S, M) \
|
|
GEN_ABSOLUTE_SYM(__##S##_##M##_##OFFSET, offsetof(S, M))
|
|
|
|
#endif /* _GEN_OFFSET_H */
|