diff options
| author | Clyne Sullivan <tullivan99@gmail.com> | 2015-09-10 11:30:41 -0400 |
|---|---|---|
| committer | Clyne Sullivan <tullivan99@gmail.com> | 2015-09-10 11:30:41 -0400 |
| commit | 3fde0e7edf310245e5658b767840e742c9341597 (patch) | |
| tree | 3fcbf69ecb959bb078078166484608e645f33f33 /include/SDL2/SDL_bits.h | |
| parent | b6ee2b7c296abcfff1ae7f7ac4db976dc4d6fd8e (diff) | |
yeah
Diffstat (limited to 'include/SDL2/SDL_bits.h')
| -rw-r--r-- | include/SDL2/SDL_bits.h | 194 |
1 files changed, 97 insertions, 97 deletions
diff --git a/include/SDL2/SDL_bits.h b/include/SDL2/SDL_bits.h index 341524f..3a8e551 100644 --- a/include/SDL2/SDL_bits.h +++ b/include/SDL2/SDL_bits.h @@ -1,97 +1,97 @@ -/* - Simple DirectMedia Layer - Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org> - - This software is provided 'as-is', without any express or implied - warranty. In no event will the authors be held liable for any damages - arising from the use of this software. - - Permission is granted to anyone to use this software for any purpose, - including commercial applications, and to alter it and redistribute it - freely, subject to the following restrictions: - - 1. The origin of this software must not be misrepresented; you must not - claim that you wrote the original software. If you use this software - in a product, an acknowledgment in the product documentation would be - appreciated but is not required. - 2. Altered source versions must be plainly marked as such, and must not be - misrepresented as being the original software. - 3. This notice may not be removed or altered from any source distribution. -*/ - -/** - * \file SDL_bits.h - * - * Functions for fiddling with bits and bitmasks. - */ - -#ifndef _SDL_bits_h -#define _SDL_bits_h - -#include "SDL_stdinc.h" - -#include "begin_code.h" -/* Set up for C function definitions, even when using C++ */ -#ifdef __cplusplus -extern "C" { -#endif - -/** - * \file SDL_bits.h - */ - -/** - * Get the index of the most significant bit. Result is undefined when called - * with 0. This operation can also be stated as "count leading zeroes" and - * "log base 2". - * - * \return Index of the most significant bit, or -1 if the value is 0. - */ -SDL_FORCE_INLINE int -SDL_MostSignificantBitIndex32(Uint32 x) -{ -#if defined(__GNUC__) && __GNUC__ >= 4 - /* Count Leading Zeroes builtin in GCC. - * http://gcc.gnu.org/onlinedocs/gcc-4.3.4/gcc/Other-Builtins.html - */ - if (x == 0) { - return -1; - } - return 31 - __builtin_clz(x); -#else - /* Based off of Bit Twiddling Hacks by Sean Eron Anderson - * <seander@cs.stanford.edu>, released in the public domain. - * http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog - */ - const Uint32 b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000}; - const int S[] = {1, 2, 4, 8, 16}; - - int msbIndex = 0; - int i; - - if (x == 0) { - return -1; - } - - for (i = 4; i >= 0; i--) - { - if (x & b[i]) - { - x >>= S[i]; - msbIndex |= S[i]; - } - } - - return msbIndex; -#endif -} - -/* Ends C function definitions when using C++ */ -#ifdef __cplusplus -} -#endif -#include "close_code.h" - -#endif /* _SDL_bits_h */ - -/* vi: set ts=4 sw=4 expandtab: */ +/*
+ Simple DirectMedia Layer
+ Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
+
+ This software is provided 'as-is', without any express or implied
+ warranty. In no event will the authors be held liable for any damages
+ arising from the use of this software.
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute it
+ freely, subject to the following restrictions:
+
+ 1. The origin of this software must not be misrepresented; you must not
+ claim that you wrote the original software. If you use this software
+ in a product, an acknowledgment in the product documentation would be
+ appreciated but is not required.
+ 2. Altered source versions must be plainly marked as such, and must not be
+ misrepresented as being the original software.
+ 3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ * \file SDL_bits.h
+ *
+ * Functions for fiddling with bits and bitmasks.
+ */
+
+#ifndef _SDL_bits_h
+#define _SDL_bits_h
+
+#include "SDL_stdinc.h"
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \file SDL_bits.h
+ */
+
+/**
+ * Get the index of the most significant bit. Result is undefined when called
+ * with 0. This operation can also be stated as "count leading zeroes" and
+ * "log base 2".
+ *
+ * \return Index of the most significant bit, or -1 if the value is 0.
+ */
+SDL_FORCE_INLINE int
+SDL_MostSignificantBitIndex32(Uint32 x)
+{
+#if defined(__GNUC__) && __GNUC__ >= 4
+ /* Count Leading Zeroes builtin in GCC.
+ * http://gcc.gnu.org/onlinedocs/gcc-4.3.4/gcc/Other-Builtins.html
+ */
+ if (x == 0) {
+ return -1;
+ }
+ return 31 - __builtin_clz(x);
+#else
+ /* Based off of Bit Twiddling Hacks by Sean Eron Anderson
+ * <seander@cs.stanford.edu>, released in the public domain.
+ * http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog
+ */
+ const Uint32 b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000};
+ const int S[] = {1, 2, 4, 8, 16};
+
+ int msbIndex = 0;
+ int i;
+
+ if (x == 0) {
+ return -1;
+ }
+
+ for (i = 4; i >= 0; i--)
+ {
+ if (x & b[i])
+ {
+ x >>= S[i];
+ msbIndex |= S[i];
+ }
+ }
+
+ return msbIndex;
+#endif
+}
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include "close_code.h"
+
+#endif /* _SDL_bits_h */
+
+/* vi: set ts=4 sw=4 expandtab: */
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