mirror of https://github.com/FFmpeg/FFmpeg.git
94 lines
2.6 KiB
C
94 lines
2.6 KiB
C
/*
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* PNG image format
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* Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
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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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#include <stdlib.h>
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#include "config.h"
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#include "libavutil/attributes.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/macros.h"
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#include "pngdsp.h"
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#if HAVE_FAST_64BIT
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#define BITS 64
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typedef uint64_t uint_native;
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#else
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#define BITS 32
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typedef uint32_t uint_native;
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#endif
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#define RN AV_JOIN(AV_RN, BITS)
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#define RNA AV_JOIN(AV_JOIN(AV_RN, BITS), A)
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#define WN AV_JOIN(AV_WN, BITS)
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// 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
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#define pb_7f (~(uint_native)0 / 255 * 0x7f)
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#define pb_80 (~(uint_native)0 / 255 * 0x80)
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static void add_bytes_l2_c(uint8_t *dst, const uint8_t *src1,
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const uint8_t *src2, int w)
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{
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long i;
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for (i = 0; i <= w - (int) sizeof(uint_native); i += sizeof(uint_native)) {
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uint_native a = RNA(src1 + i);
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uint_native b = RN (src2 + i);
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WN(dst + i, ((a & pb_7f) + (b & pb_7f)) ^ ((a ^ b) & pb_80));
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}
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for (; i < w; i++)
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dst[i] = src1[i] + src2[i];
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}
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void ff_png_add_paeth_prediction(uint8_t *dst, const uint8_t *src,
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const uint8_t *top, int w, int bpp)
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{
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for (int i = 0; i < w; ++i) {
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int a, b, c, p, pa, pb, pc;
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a = dst[i - bpp];
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b = top[i];
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c = top[i - bpp];
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p = b - c;
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pc = a - c;
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pa = abs(p);
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pb = abs(pc);
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pc = abs(p + pc);
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if (pa <= pb && pa <= pc)
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p = a;
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else if (pb <= pc)
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p = b;
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else
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p = c;
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dst[i] = p + src[i];
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}
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}
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av_cold void ff_pngdsp_init(PNGDSPContext *dsp)
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{
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dsp->add_bytes_l2 = add_bytes_l2_c;
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dsp->add_paeth_prediction = ff_png_add_paeth_prediction;
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#if ARCH_X86 && HAVE_X86ASM
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ff_pngdsp_init_x86(dsp);
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#endif
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}
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