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Diffstat (limited to 'protocol/lufa/LUFA-120730/LUFA/Common/CompilerSpecific.h')
| -rw-r--r-- | protocol/lufa/LUFA-120730/LUFA/Common/CompilerSpecific.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/protocol/lufa/LUFA-120730/LUFA/Common/CompilerSpecific.h b/protocol/lufa/LUFA-120730/LUFA/Common/CompilerSpecific.h new file mode 100644 index 0000000000..22afe940b3 --- /dev/null +++ b/protocol/lufa/LUFA-120730/LUFA/Common/CompilerSpecific.h @@ -0,0 +1,97 @@ +/*
+ LUFA Library
+ Copyright (C) Dean Camera, 2012.
+
+ dean [at] fourwalledcubicle [dot] com
+ www.lufa-lib.org
+*/
+
+/*
+ Copyright 2012 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 disclaim 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 true if the given value is known to be a compile time constant, 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
+
+/** @} */
+
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