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mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-28 20:53:54 +02:00
FFmpeg/libavcodec/pngdsp.c
Andreas Rheinhardt 9e4e8ae1e6 avcodec/pngdsp: Fix unaligned accesses, effective type violations
Affected the lscr fate-test (only visible on x86 if
the SSE2 is disabled).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2024-04-02 00:21:58 +02:00

65 lines
2.0 KiB
C

/*
* 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 "config.h"
#include "libavutil/attributes.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/macros.h"
#include "png.h"
#include "pngdsp.h"
#if HAVE_FAST_64BIT
#define BITS 64
typedef uint64_t uint_native;
#else
#define BITS 32
typedef uint32_t uint_native;
#endif
#define RN AV_JOIN(AV_RN, BITS)
#define RNA AV_JOIN(AV_JOIN(AV_RN, BITS), A)
#define WN AV_JOIN(AV_WN, BITS)
// 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
#define pb_7f (~(uint_native)0 / 255 * 0x7f)
#define pb_80 (~(uint_native)0 / 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(uint_native); i += sizeof(uint_native)) {
uint_native a = RNA(src1 + i);
uint_native b = RN (src2 + i);
WN(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);
#endif
}