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Code Issues Releases Activity

move the +400 out of the innermost loop

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Originally committed as revision 6086 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2006-08-25 13:46:56 +00:00
parent 9b49f89cdf
commit bc2d2757bb
1 changed files with 12 additions and 11 deletions
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23
libavcodec/mpegaudiodec.c
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@ -423,7 +423,7 @@ static int decode_init(AVCodecContext * avctx)
f = pow((double)(i/4), 4.0 / 3.0) * pow(2, (i&3)*0.25);
fm = frexp(f, &e);
m = (uint32_t)(fm*(1LL<<31) + 0.5);
e+= FRAC_BITS - 31 + 5;
e+= FRAC_BITS - 31 + 5 - 100;
/* normalized to FRAC_BITS */
table_4_3_value[i] = m;
@ -431,11 +431,11 @@ static int decode_init(AVCodecContext * avctx)
table_4_3_exp[i] = -e;
}
for(i=0; i<512*16; i++){
int exponent= (i>>4)-400;
double f= pow(i&15, 4.0 / 3.0) * pow(2, exponent*0.25 + FRAC_BITS + 5);
expval_table[exponent+400][i&15]= lrintf(f);
int exponent= (i>>4);
double f= pow(i&15, 4.0 / 3.0) * pow(2, (exponent-400)*0.25 + FRAC_BITS + 5);
expval_table[exponent][i&15]= lrintf(f);
if((i&15)==1)
exp_table[exponent+400]= lrintf(f);
exp_table[exponent]= lrintf(f);
}
for(i=0;i<7;i++) {
@ -1643,7 +1643,7 @@ static void exponents_from_scale_factors(MPADecodeContext *s,
bstab = band_size_long[s->sample_rate_index];
pretab = mpa_pretab[g->preflag];
for(i=0;i<g->long_end;i++) {
v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift);
v0 = gain - ((g->scale_factors[i] + pretab[i]) << shift) + 400;
len = bstab[i];
for(j=len;j>0;j--)
*exp_ptr++ = v0;
@ -1658,7 +1658,7 @@ static void exponents_from_scale_factors(MPADecodeContext *s,
for(i=g->short_start;i<13;i++) {
len = bstab[i];
for(l=0;l<3;l++) {
v0 = gains[l] - (g->scale_factors[k++] << shift);
v0 = gains[l] - (g->scale_factors[k++] << shift) + 400;
for(j=len;j>0;j--)
*exp_ptr++ = v0;
}
@ -1729,8 +1729,8 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
v = l3_unscale(x, exponent);
#else
if (x < 15){
v = expval_table[ exponent + 400 ][ x ];
// v = expval_table[ (exponent&3) + 400 ][ x ] >> FFMIN(0 - (exponent>>2), 31);
v = expval_table[ exponent ][ x ];
// v = expval_table[ (exponent&3) ][ x ] >> FFMIN(0 - (exponent>>2), 31);
}else{
x += get_bitsz(&s->gb, linbits);
v = l3_unscale(x, exponent);
@ -1749,7 +1749,7 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
v = l3_unscale(y, exponent);
#else
if (y < 15){
v = expval_table[ exponent + 400 ][ y ];
v = expval_table[ exponent ][ y ];
}else{
y += get_bitsz(&s->gb, linbits);
v = l3_unscale(y, exponent);
@ -1791,7 +1791,8 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
const static int idxtab[16]={3,3,2,2,1,1,1,1,0,0,0,0,0,0,0,0};
int pos= s_index+idxtab[code];
code ^= 8>>idxtab[code];
v = exp_table[ exponents[pos] + 400];
v = exp_table[ exponents[pos] ];
// v = exp_table[ (exponents[pos]&3) ] >> FFMIN(0 - (exponents[pos]>>2), 31);
if(get_bits1(&s->gb))
v = -v;
g->sb_hybrid[pos] = v;