mirror of
https://github.com/FFmpeg/FFmpeg.git
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142 lines
3.4 KiB
C
142 lines
3.4 KiB
C
/*
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* Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVUTIL_INTMATH_H
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#define AVUTIL_INTMATH_H
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#include <stdint.h>
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#include "config.h"
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#include "attributes.h"
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#if ARCH_ARM
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# include "arm/intmath.h"
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#endif
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#if ARCH_X86
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# include "x86/intmath.h"
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#endif
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#if HAVE_FAST_CLZ
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#if AV_GCC_VERSION_AT_LEAST(3,4)
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#ifndef ff_log2
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# define ff_log2(x) (31 - __builtin_clz((x)|1))
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# ifndef ff_log2_16bit
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# define ff_log2_16bit av_log2
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# endif
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#endif /* ff_log2 */
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#endif /* AV_GCC_VERSION_AT_LEAST(3,4) */
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#endif
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extern const uint8_t ff_log2_tab[256];
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#ifndef ff_log2
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#define ff_log2 ff_log2_c
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static av_always_inline av_const int ff_log2_c(unsigned int v)
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{
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int n = 0;
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if (v & 0xffff0000) {
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v >>= 16;
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n += 16;
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}
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if (v & 0xff00) {
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v >>= 8;
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n += 8;
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}
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n += ff_log2_tab[v];
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return n;
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}
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#endif
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#ifndef ff_log2_16bit
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#define ff_log2_16bit ff_log2_16bit_c
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static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
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{
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int n = 0;
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if (v & 0xff00) {
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v >>= 8;
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n += 8;
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}
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n += ff_log2_tab[v];
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return n;
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}
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#endif
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#define av_log2 ff_log2
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#define av_log2_16bit ff_log2_16bit
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/**
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* @addtogroup lavu_math
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* @{
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*/
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#if HAVE_FAST_CLZ
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#if AV_GCC_VERSION_AT_LEAST(3,4)
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#ifndef ff_ctz
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#define ff_ctz(v) __builtin_ctz(v)
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#endif
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#ifndef ff_ctzll
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#define ff_ctzll(v) __builtin_ctzll(v)
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#endif
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#endif
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#endif
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#ifndef ff_ctz
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#define ff_ctz ff_ctz_c
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/**
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* Trailing zero bit count.
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*
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* @param v input value. If v is 0, the result is undefined.
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* @return the number of trailing 0-bits
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*/
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/* We use the De-Bruijn method outlined in:
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* http://supertech.csail.mit.edu/papers/debruijn.pdf. */
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static av_always_inline av_const int ff_ctz_c(int v)
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{
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static const uint8_t debruijn_ctz32[32] = {
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0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
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31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
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};
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return debruijn_ctz32[(uint32_t)((v & -v) * 0x077CB531U) >> 27];
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}
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#endif
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#ifndef ff_ctzll
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#define ff_ctzll ff_ctzll_c
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/* We use the De-Bruijn method outlined in:
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* http://supertech.csail.mit.edu/papers/debruijn.pdf. */
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static av_always_inline av_const int ff_ctzll_c(long long v)
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{
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static const uint8_t debruijn_ctz64[64] = {
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0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
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62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
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63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
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51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
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};
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return debruijn_ctz64[(uint64_t)((v & -v) * 0x022FDD63CC95386D) >> 58];
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}
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#endif
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/**
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* @}
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*/
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#endif /* AVUTIL_INTMATH_H */
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