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optimizing av_log2

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Originally committed as revision 1515 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer
2003-01-27 20:39:29 +00:00
parent 425ed6e223
commit c81f034988
2 changed files with 30 additions and 12 deletions
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11
libavcodec/common.c
View File

@@ -27,6 +27,17 @@ const UINT8 ff_sqrt_tab[128]={
9, 9, 9, 9,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,11,11,11,11,11,11,11
};
const uint8_t ff_log2_tab[256]={
0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
};
void init_put_bits(PutBitContext *s,
UINT8 *buffer, int buffer_size,
void *opaque,

31
libavcodec/common.h
View File

@@ -804,6 +804,7 @@ void print_stats(void);
#endif
/* misc math functions */
extern const uint8_t ff_log2_tab[256];
static inline int av_log2(unsigned int v)
{
@@ -818,20 +819,26 @@ static inline int av_log2(unsigned int v)
v >>= 8;
n += 8;
}
if (v & 0xf0) {
v >>= 4;
n += 4;
}
if (v & 0xc) {
v >>= 2;
n += 2;
}
if (v & 0x2) {
n++;
}
n += ff_log2_tab[v];
return n;
}
static inline int av_log2_16bit(unsigned int v)
{
int n;
n = 0;
if (v & 0xff00) {
v >>= 8;
n += 8;
}
n += ff_log2_tab[v];
return n;
}
/* median of 3 */
static inline int mid_pred(int a, int b, int c)
{
@@ -861,7 +868,7 @@ static inline int clip(int a, int amin, int amax)
}
/* math */
extern const UINT8 ff_sqrt_tab[128];
extern const uint8_t ff_sqrt_tab[128];
int ff_gcd(int a, int b);