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avcodec/xbmdec: Use LUT for hex char->number conversion 

Improves performance by about 30%.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-03-06 22:49:54 +01:00
parent 8fb89790af
commit 0b2ed7f6c7
1 changed files with 15 additions and 10 deletions
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25
libavcodec/xbmdec.c
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@ -28,17 +28,22 @@
static int get_nibble(uint8_t x)
{
int ret = 255;
#define TIMES256(idx) \
TIMES64(4 * (idx)) TIMES64(4 * (idx) + 1) TIMES64(4 * (idx) + 2) TIMES64(4 * (idx) + 3)
#define TIMES64(idx) \
TIMES16(4 * (idx)) TIMES16(4 * (idx) + 1) TIMES16(4 * (idx) + 2) TIMES16(4 * (idx) + 3)
#define TIMES16(idx) \
TIMES4(4 * (idx)) TIMES4(4 * (idx) + 1) TIMES4(4 * (idx) + 2) TIMES4(4 * (idx) + 3)
#define TIMES4(idx) \
ENTRY(4 * (idx)) ENTRY(4 * (idx) + 1) ENTRY(4 * (idx) + 2) ENTRY(4 * (idx) + 3)
#define ENTRY(x) [x] = ((x) >= 'a' && (x) <= 'f') ? (x) - ('a' - 10) : \
((x) >= 'A' && (x) <= 'F') ? (x) - ('A' - 10) : \
((x) >= '0' && (x) <= '9') ? (x) - '0' : 255,
if (x <= '9') {
if (x >= '0')
ret = x - '0';
} else if (x >= 'a') {
if (x <= 'f')
ret = x - ('a' - 10);
} else if (x >= 'A' && x <= 'F')
ret = x - ('A' - 10);
return ret;
static const uint8_t lut[] = {
TIMES256(0)
};
return lut[x];
}
static int parse_str_int(const uint8_t *p, const uint8_t *end, const uint8_t *key)