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FFmpeg/libavcodec/lossless_videoencdsp.c
Andreas Rheinhardt cc2d2b665e avcodec/lossless_videoencdsp: Fix unaligned access
HAVE_FAST_UNALIGNED being true does not imply that
one can simply read from any pointer via *(long*).
It is undefined behaviour in case the pointer is not
sufficiently aligned; and even if it is, it is (likely)
a violation of the effective-type rules. Fix both
of these by using the appropriate AV_[RW]N macros.

Also, the current code used sizeof(long) as if this
were the CPU's native arithmetic size, but this is
not true on 64bit Windows. This has been fixed, too.

This affected huffyuv FATE-tests.

Tested-by: Sean McGovern <gseanmcg@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2024-03-14 21:22:45 +01:00

114 lines
3.4 KiB
C

/*
* 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 "lossless_videoencdsp.h"
#include "mathops.h"
#if HAVE_FAST_64BIT
typedef uint64_t uint_native;
#define READ AV_RN64
#define READA AV_RN64A
#define WRITEA AV_WN64A
#else
typedef uint32_t uint_native;
#define READ AV_RN32
#define READA AV_RN32A
#define WRITEA AV_WN32A
#endif
// 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 diff_bytes_c(uint8_t *dst, const uint8_t *src1, const uint8_t *src2, intptr_t w)
{
long i;
#if !HAVE_FAST_UNALIGNED
if (((uintptr_t)src1 | (uintptr_t)src2) & (sizeof(uint_native) - 1)) {
for (i = 0; i + 7 < w; i += 8) {
dst[i + 0] = src1[i + 0] - src2[i + 0];
dst[i + 1] = src1[i + 1] - src2[i + 1];
dst[i + 2] = src1[i + 2] - src2[i + 2];
dst[i + 3] = src1[i + 3] - src2[i + 3];
dst[i + 4] = src1[i + 4] - src2[i + 4];
dst[i + 5] = src1[i + 5] - src2[i + 5];
dst[i + 6] = src1[i + 6] - src2[i + 6];
dst[i + 7] = src1[i + 7] - src2[i + 7];
}
} else
#endif
for (i = 0; i <= w - (int) sizeof(uint_native); i += sizeof(uint_native)) {
uint_native a = READA(src1 + i);
uint_native b = READ(src2 + i);
WRITEA(dst + i, ((a | pb_80) - (b & pb_7f)) ^ ((a ^ b ^ pb_80) & pb_80));
}
for (; i < w; i++)
dst[i + 0] = src1[i + 0] - src2[i + 0];
}
static void sub_median_pred_c(uint8_t *dst, const uint8_t *src1,
const uint8_t *src2, intptr_t w,
int *left, int *left_top)
{
int i;
uint8_t l, lt;
l = *left;
lt = *left_top;
for (i = 0; i < w; i++) {
const int pred = mid_pred(l, src1[i], (l + src1[i] - lt) & 0xFF);
lt = src1[i];
l = src2[i];
dst[i] = l - pred;
}
*left = l;
*left_top = lt;
}
static void sub_left_predict_c(uint8_t *dst, const uint8_t *src,
ptrdiff_t stride, ptrdiff_t width, int height)
{
int i, j;
uint8_t prev = 0x80; /* Set the initial value */
for (j = 0; j < height; j++) {
for (i = 0; i < width; i++) {
*dst++ = src[i] - prev;
prev = src[i];
}
src += stride;
}
}
av_cold void ff_llvidencdsp_init(LLVidEncDSPContext *c)
{
c->diff_bytes = diff_bytes_c;
c->sub_median_pred = sub_median_pred_c;
c->sub_left_predict = sub_left_predict_c;
#if ARCH_RISCV
ff_llvidencdsp_init_riscv(c);
#elif ARCH_X86
ff_llvidencdsp_init_x86(c);
#endif
}