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avcodec/pngdec: Optimize has_trns code

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add inner loop specialisations for 2 bpp and 4 bpp
These are all cases for which i found testsamples.

30M cycles -> 5M cycles

Testcase: fate-rgbapng-4816
Testcase: 16097/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-5664690889293824

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-08-18 01:28:38 +02:00
parent 8ae5d2cbb2
commit 361b3c873e
1 changed files with 29 additions and 8 deletions
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37
libavcodec/pngdec.c
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@ -24,6 +24,7 @@
#include "libavutil/avassert.h"
#include "libavutil/bprint.h"
#include "libavutil/imgutils.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/stereo3d.h"
#include "libavutil/mastering_display_metadata.h"
@ -1367,15 +1368,35 @@ exit_loop:
for (y = 0; y < s->height; ++y) {
uint8_t *row = &s->image_buf[s->image_linesize * y];
/* since we're updating in-place, we have to go from right to left */
for (x = s->width; x > 0; --x) {
uint8_t *pixel = &row[s->bpp * (x - 1)];
memmove(pixel, &row[raw_bpp * (x - 1)], raw_bpp);
if (s->bpp == 2 && byte_depth == 1) {
uint8_t *pixel = &row[2 * s->width - 1];
uint8_t *rowp = &row[1 * s->width - 1];
int tcolor = s->transparent_color_be[0];
for (x = s->width; x > 0; --x) {
*pixel-- = *rowp == tcolor ? 0 : 0xff;
*pixel-- = *rowp--;
}
} else if (s->bpp == 4 && byte_depth == 1) {
uint8_t *pixel = &row[4 * s->width - 1];
uint8_t *rowp = &row[3 * s->width - 1];
int tcolor = AV_RL24(s->transparent_color_be);
for (x = s->width; x > 0; --x) {
*pixel-- = AV_RL24(rowp-2) == tcolor ? 0 : 0xff;
*pixel-- = *rowp--;
*pixel-- = *rowp--;
*pixel-- = *rowp--;
}
} else {
/* since we're updating in-place, we have to go from right to left */
for (x = s->width; x > 0; --x) {
uint8_t *pixel = &row[s->bpp * (x - 1)];
memmove(pixel, &row[raw_bpp * (x - 1)], raw_bpp);
if (!memcmp(pixel, s->transparent_color_be, raw_bpp)) {
memset(&pixel[raw_bpp], 0, byte_depth);
} else {
memset(&pixel[raw_bpp], 0xff, byte_depth);
if (!memcmp(pixel, s->transparent_color_be, raw_bpp)) {
memset(&pixel[raw_bpp], 0, byte_depth);
} else {
memset(&pixel[raw_bpp], 0xff, byte_depth);
}
}
}
}