aac5773f
 hucm
功能基本完成，接口待打磨
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/*
* PNG image format
* Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "png.h"
#include "pngdsp.h"
// 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
#define pb_7f (~0UL / 255 * 0x7f)
#define pb_80 (~0UL / 255 * 0x80)
static void add_bytes_l2_c(uint8_t *dst, uint8_t *src1, uint8_t *src2, int w)
{
long i;
for (i = 0; i <= w - (int) sizeof(long); i += sizeof(long)) {
long a = *(long *)(src1 + i);
long b = *(long *)(src2 + i);
*(long *)(dst + i) = ((a & pb_7f) + (b & pb_7f)) ^ ((a ^ b) & pb_80);
}
for (; i < w; i++)
dst[i] = src1[i] + src2[i];
}
av_cold void ff_pngdsp_init(PNGDSPContext *dsp)
{
dsp->add_bytes_l2 = add_bytes_l2_c;
dsp->add_paeth_prediction = ff_add_png_paeth_prediction;
if (ARCH_X86)
ff_pngdsp_init_x86(dsp);
}
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