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avcodec/scpr: optimize shift loop.

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Speeds code up from 50sec to 15sec

Fixes Timeout
Fixes: 3242/clusterfuzz-testcase-5811951672229888

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 981f04b2ae)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2017-09-08 23:29:13 +02:00
parent 8eb8882af5
commit b590758298
1 changed files with 12 additions and 1 deletions
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13
libavcodec/scpr.c
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@ -824,8 +824,19 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
if (ret < 0)
return ret;
// scale up each sample by 8
for (y = 0; y < avctx->height; y++) {
for (x = 0; x < avctx->width * 4; x++) {
// If the image is sufficiently aligned, compute 8 samples at once
if (!(((uintptr_t)dst) & 7)) {
uint64_t *dst64 = (uint64_t *)dst;
int w = avctx->width>>1;
for (x = 0; x < w; x++) {
dst64[x] = (dst64[x] << 3) & 0xFCFCFCFCFCFCFCFCULL;
}
x *= 8;
} else
x = 0;
for (; x < avctx->width * 4; x++) {
dst[x] = dst[x] << 3;
}
dst += frame->linesize[0];