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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>
101 lines
3.1 KiB
C
101 lines
3.1 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 "lossless_videoencdsp.h"
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#include "mathops.h"
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// 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
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#define pb_7f (~0UL / 255 * 0x7f)
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#define pb_80 (~0UL / 255 * 0x80)
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static void diff_bytes_c(uint8_t *dst, const uint8_t *src1, const uint8_t *src2, intptr_t w)
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{
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long i;
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#if !HAVE_FAST_UNALIGNED
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if (((long)src1 | (long)src2) & (sizeof(long) - 1)) {
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for (i = 0; i + 7 < w; i += 8) {
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dst[i + 0] = src1[i + 0] - src2[i + 0];
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dst[i + 1] = src1[i + 1] - src2[i + 1];
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dst[i + 2] = src1[i + 2] - src2[i + 2];
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dst[i + 3] = src1[i + 3] - src2[i + 3];
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dst[i + 4] = src1[i + 4] - src2[i + 4];
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dst[i + 5] = src1[i + 5] - src2[i + 5];
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dst[i + 6] = src1[i + 6] - src2[i + 6];
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dst[i + 7] = src1[i + 7] - src2[i + 7];
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}
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} else
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#endif
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for (i = 0; i <= w - (int) sizeof(long); i += sizeof(long)) {
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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 | pb_80) - (b & pb_7f)) ^
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((a ^ b ^ pb_80) & pb_80);
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}
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for (; i < w; i++)
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dst[i + 0] = src1[i + 0] - src2[i + 0];
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}
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static void sub_median_pred_c(uint8_t *dst, const uint8_t *src1,
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const uint8_t *src2, intptr_t w,
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int *left, int *left_top)
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{
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int i;
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uint8_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) & 0xFF);
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lt = src1[i];
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l = src2[i];
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dst[i] = l - pred;
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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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static void sub_left_predict_c(uint8_t *dst, uint8_t *src,
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ptrdiff_t stride, ptrdiff_t width, int height)
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{
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int i, j;
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uint8_t prev = 0x80; /* Set the initial value */
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for (j = 0; j < height; j++) {
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for (i = 0; i < width; i++) {
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*dst++ = src[i] - prev;
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prev = src[i];
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}
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src += stride;
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}
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}
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av_cold void ff_llvidencdsp_init(LLVidEncDSPContext *c)
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{
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c->diff_bytes = diff_bytes_c;
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c->sub_median_pred = sub_median_pred_c;
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c->sub_left_predict = sub_left_predict_c;
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#if ARCH_X86
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ff_llvidencdsp_init_x86(c);
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#endif
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}
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