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https://github.com/FFmpeg/FFmpeg.git
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40e6575aa3
This is more spec-compliant because it does not rely on dead-code elimination by the compiler. Especially MSVC has problems with this, as can be seen in https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/296373.html or https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/297022.html This commit does not eliminate every instance where we rely on dead code elimination: It only tackles branching to the initialization of arch-specific dsp code, not e.g. all uses of CONFIG_ and HAVE_ checks. But maybe it is already enough to compile FFmpeg with MSVC with whole-programm-optimizations enabled (if one does not disable too many components). Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/*
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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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#include "config.h"
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#include "libavutil/attributes.h"
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#include "huffyuvencdsp.h"
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#include "mathops.h"
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// 0x00010001 or 0x0001000100010001 or whatever, depending on the cpu's native arithmetic size
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#define pw_1 (ULONG_MAX / UINT16_MAX)
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static void diff_int16_c(uint16_t *dst, const uint16_t *src1, const uint16_t *src2, unsigned mask, int w){
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long i;
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#if !HAVE_FAST_UNALIGNED
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if((long)src2 & (sizeof(long)-1)){
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for(i=0; i+3<w; i+=4){
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dst[i+0] = (src1[i+0]-src2[i+0]) & mask;
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dst[i+1] = (src1[i+1]-src2[i+1]) & mask;
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dst[i+2] = (src1[i+2]-src2[i+2]) & mask;
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dst[i+3] = (src1[i+3]-src2[i+3]) & mask;
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}
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}else
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#endif
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{
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unsigned long pw_lsb = (mask >> 1) * pw_1;
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unsigned long pw_msb = pw_lsb + pw_1;
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for (i = 0; i <= w - (int)sizeof(long)/2; i += sizeof(long)/2) {
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long a = *(long*)(src1+i);
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long b = *(long*)(src2+i);
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*(long*)(dst+i) = ((a|pw_msb) - (b&pw_lsb)) ^ ((a^b^pw_msb)&pw_msb);
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}
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}
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for (; i<w; i++)
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dst[i] = (src1[i] - src2[i]) & mask;
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}
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static void sub_hfyu_median_pred_int16_c(uint16_t *dst, const uint16_t *src1, const uint16_t *src2, unsigned mask, int w, int *left, int *left_top){
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int i;
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uint16_t l, lt;
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l = *left;
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lt = *left_top;
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for(i=0; i<w; i++){
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const int pred = mid_pred(l, src1[i], (l + src1[i] - lt) & mask);
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lt = src1[i];
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l = src2[i];
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dst[i] = (l - pred) & mask;
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}
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*left = l;
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*left_top = lt;
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}
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av_cold void ff_huffyuvencdsp_init(HuffYUVEncDSPContext *c, AVCodecContext *avctx)
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{
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c->diff_int16 = diff_int16_c;
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c->sub_hfyu_median_pred_int16 = sub_hfyu_median_pred_int16_c;
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#if ARCH_X86
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ff_huffyuvencdsp_init_x86(c, avctx);
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#endif
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}
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