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https://github.com/scp-fs2open/fs2open.github.com.git
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FSCyborg
1f41d98e2a
This should fix #1886. I built it and it fixes the immediate problem. Only two of the documentation files we have in the codebase were actually updated. Verison name in prebuilt.cmake also needed to be changed due to prebuild SDL version changing during upgrade to the prebuild repository.
122 lines
3.0 KiB
C
122 lines
3.0 KiB
C
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2019 Sam Lantinga <[email protected]>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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/**
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* \file SDL_bits.h
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*
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* Functions for fiddling with bits and bitmasks.
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*/
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#ifndef SDL_bits_h_
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#define SDL_bits_h_
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#include "SDL_stdinc.h"
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#include "begin_code.h"
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/* Set up for C function definitions, even when using C++ */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* \file SDL_bits.h
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*/
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/**
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* Get the index of the most significant bit. Result is undefined when called
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* with 0. This operation can also be stated as "count leading zeroes" and
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* "log base 2".
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*
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* \return Index of the most significant bit, or -1 if the value is 0.
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*/
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#if defined(__WATCOMC__) && defined(__386__)
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extern _inline int _SDL_clz_watcom (Uint32);
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#pragma aux _SDL_clz_watcom = \
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"bsr eax, eax" \
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"xor eax, 31" \
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parm [eax] nomemory \
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value [eax] \
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modify exact [eax] nomemory;
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#endif
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SDL_FORCE_INLINE int
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SDL_MostSignificantBitIndex32(Uint32 x)
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{
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#if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
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/* Count Leading Zeroes builtin in GCC.
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* http://gcc.gnu.org/onlinedocs/gcc-4.3.4/gcc/Other-Builtins.html
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*/
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if (x == 0) {
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return -1;
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}
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return 31 - __builtin_clz(x);
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#elif defined(__WATCOMC__) && defined(__386__)
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if (x == 0) {
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return -1;
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}
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return 31 - _SDL_clz_watcom(x);
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#else
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/* Based off of Bit Twiddling Hacks by Sean Eron Anderson
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* <[email protected]>, released in the public domain.
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* http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog
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*/
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const Uint32 b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000};
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const int S[] = {1, 2, 4, 8, 16};
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int msbIndex = 0;
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int i;
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if (x == 0) {
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return -1;
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}
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for (i = 4; i >= 0; i--)
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{
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if (x & b[i])
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{
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x >>= S[i];
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msbIndex |= S[i];
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}
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}
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return msbIndex;
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#endif
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}
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SDL_FORCE_INLINE SDL_bool
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SDL_HasExactlyOneBitSet32(Uint32 x)
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{
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if (x && !(x & (x - 1))) {
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return SDL_TRUE;
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}
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return SDL_FALSE;
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}
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/* Ends C function definitions when using C++ */
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#ifdef __cplusplus
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}
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#endif
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#include "close_code.h"
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#endif /* SDL_bits_h_ */
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/* vi: set ts=4 sw=4 expandtab: */
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