Split out compiler specific helper macros into a new CompilerSpecific.h header file inside the library, for future expansion.

1 files changed, 96 insertions, 0 deletions

diff --git a/LUFA/Common/CompilerSpecific.h b/LUFA/Common/CompilerSpecific.h
new file mode 100644
index 000000000..ee6db461b
--- /dev/null
+++ b/LUFA/Common/CompilerSpecific.h
@@ -0,0 +1,96 @@
+/*

+             LUFA Library

+     Copyright (C) Dean Camera, 2011.

+

+  dean [at] fourwalledcubicle [dot] com

+           www.lufa-lib.org

+*/

+

+/*

+  Copyright 2011  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 macros 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 Macros

+ *  \brief Compiler specific macros for code optimization and correctness.

+ *

+ *  Compiler specific macros 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");

+				

+				/** Evaluates to boolean true 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.

+				 */

+				#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

+