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Diffstat (limited to 'LUFA/Common/CompilerSpecific.h')
| -rw-r--r-- | LUFA/Common/CompilerSpecific.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/LUFA/Common/CompilerSpecific.h b/LUFA/Common/CompilerSpecific.h new file mode 100644 index 0000000000..41e5305b1d --- /dev/null +++ b/LUFA/Common/CompilerSpecific.h @@ -0,0 +1,97 @@ +/* + LUFA Library + Copyright (C) Dean Camera, 2017. + + dean [at] fourwalledcubicle [dot] com + www.lufa-lib.org +*/ + +/* + Copyright 2017 Dean Camera (dean [at] fourwalledcubicle [dot] com) + + Permission to use, copy, modify, distribute, and sell this + software and its documentation for any purpose is hereby granted + without fee, provided that the above copyright notice appear in + all copies and that both that the copyright notice and this + permission notice and warranty disclaimer appear in supporting + documentation, and that the name of the author not be used in + advertising or publicity pertaining to distribution of the + software without specific, written prior permission. + + The author disclaims all warranties with regard to this + software, including all implied warranties of merchantability + and fitness. In no event shall the author be liable for any + special, indirect or consequential damages or any damages + whatsoever resulting from loss of use, data or profits, whether + in an action of contract, negligence or other tortious action, + arising out of or in connection with the use or performance of + this software. +*/ + +/** \file + * \brief Compiler specific definitions for code optimization and correctness. + * + * \copydetails Group_CompilerSpecific + * + * \note Do not include this file directly, rather include the Common.h header file instead to gain this file's + * functionality. + */ + +/** \ingroup Group_Common + * \defgroup Group_CompilerSpecific Compiler Specific Definitions + * \brief Compiler specific definitions for code optimization and correctness. + * + * Compiler specific definitions to expose certain compiler features which may increase the level of code optimization + * for a specific compiler, or correct certain issues that may be present such as memory barriers for use in conjunction + * with atomic variable access. + * + * Where possible, on alternative compilers, these macros will either have no effect, or default to returning a sane value + * so that they can be used in existing code without the need for extra compiler checks in the user application code. + * + * @{ + */ + +#ifndef __LUFA_COMPILERSPEC_H__ +#define __LUFA_COMPILERSPEC_H__ + + /* Preprocessor Checks: */ + #if !defined(__INCLUDE_FROM_COMMON_H) + #error Do not include this file directly. Include LUFA/Common/Common.h instead to gain this functionality. + #endif + + /* Public Interface - May be used in end-application: */ + /* Macros: */ + #if defined(__GNUC__) || defined(__DOXYGEN__) + /** Forces GCC to use pointer indirection (via the device's pointer register pairs) when accessing the given + * struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through + * a pointer, resulting in a larger binary. When this macro is used on a (non \c const) structure pointer before + * use, it will force GCC to use pointer indirection on the elements rather than direct store and load + * instructions. + * + * \param[in, out] StructPtr Pointer to a structure which is to be forced into indirect access mode. + */ + #define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr)) + + /** Forces GCC to create a memory barrier, ensuring that memory accesses are not reordered past the barrier point. + * This can be used before ordering-critical operations, to ensure that the compiler does not re-order the resulting + * assembly output in an unexpected manner on sections of code that are ordering-specific. + */ + #define GCC_MEMORY_BARRIER() __asm__ __volatile__("" ::: "memory"); + + /** Determines if the specified value can be determined at compile-time to be a constant value when compiling under GCC. + * + * \param[in] x Value to check compile-time constantness of. + * + * \return Boolean \c true if the given value is known to be a compile time constant, \c false otherwise. + */ + #define GCC_IS_COMPILE_CONST(x) __builtin_constant_p(x) + #else + #define GCC_FORCE_POINTER_ACCESS(StructPtr) + #define GCC_MEMORY_BARRIER() + #define GCC_IS_COMPILE_CONST(x) 0 + #endif + +#endif + +/** @} */ + |