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

Speeds up decoding and also reduces binary size.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-03-06 23:16:22 +01:00
parent 0b2ed7f6c7
commit 9e36e2fb7b
1 changed files with 16 additions and 9 deletions
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25
libavcodec/xpmdec.c
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@ -193,15 +193,22 @@ static const ColorEntry color_table[] = {
static unsigned hex_char_to_number(uint8_t x) static unsigned hex_char_to_number(uint8_t x)
{ {
if (x >= 'a' && x <= 'f') #define TIMES256(idx) \
x -= 'a' - 10; TIMES64(4 * (idx)) TIMES64(4 * (idx) + 1) TIMES64(4 * (idx) + 2) TIMES64(4 * (idx) + 3)
else if (x >= 'A' && x <= 'F') #define TIMES64(idx) \
x -= 'A' - 10; TIMES16(4 * (idx)) TIMES16(4 * (idx) + 1) TIMES16(4 * (idx) + 2) TIMES16(4 * (idx) + 3)
else if (x >= '0' && x <= '9') #define TIMES16(idx) \
x -= '0'; TIMES4(4 * (idx)) TIMES4(4 * (idx) + 1) TIMES4(4 * (idx) + 2) TIMES4(4 * (idx) + 3)
else #define TIMES4(idx) \
x = 0; ENTRY(4 * (idx)) ENTRY(4 * (idx) + 1) ENTRY(4 * (idx) + 2) ENTRY(4 * (idx) + 3)
return x; #define ENTRY(x) [x] = ((x) >= 'a' && (x) <= 'f') ? (x) - ('a' - 10) : \
((x) >= 'A' && (x) <= 'F') ? (x) - ('A' - 10) : \
((x) >= '0' && (x) <= '9') ? (x) - '0' : 0,
static const uint8_t lut[] = {
TIMES256(0)
};
return lut[x];
} }
/* /*