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author | Marcoen Hirschberg <marcoen@gmail.com> | 2007-09-20 17:35:36 +0000 |
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committer | Marcoen Hirschberg <marcoen@gmail.com> | 2007-09-20 17:35:36 +0000 |
commit | 6475ad7821c4e072e8e549258cf05bfddbb82f97 (patch) | |
tree | 9393c55b2d371f739ba7cf687f682428a1c91585 | |
parent | 46c2363889e15444546f991ef5775c34aea02919 (diff) | |
download | rockbox-6475ad7821c4e072e8e549258cf05bfddbb82f97.tar.gz rockbox-6475ad7821c4e072e8e549258cf05bfddbb82f97.zip |
reuse the largest sin and cos tables for smaller sizes
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14786 a1c6a512-1295-4272-9138-f99709370657
-rw-r--r-- | apps/codecs/libwma/mdct.c | 56 |
1 files changed, 24 insertions, 32 deletions
diff --git a/apps/codecs/libwma/mdct.c b/apps/codecs/libwma/mdct.c index ac30def6dd..838bda47a7 100644 --- a/apps/codecs/libwma/mdct.c +++ b/apps/codecs/libwma/mdct.c @@ -22,10 +22,7 @@ #include "wmafixed.h" #include "fft.h" -fixed32 *tcosarray[5], *tsinarray[5]; -fixed32 tcos0[1024], tcos1[512], tcos2[256], tcos3[128], tcos4[64]; //these are the sin and cos rotations used by the MDCT -fixed32 tsin0[1024], tsin1[512], tsin2[256], tsin3[128], tsin4[64]; - +fixed32 tcos0[1024], tsin0[1024]; //these are the sin and cos rotations used by the MDCT uint16_t revtab0[1024]; /** @@ -33,32 +30,16 @@ uint16_t revtab0[1024]; */ int ff_mdct_init(MDCTContext *s, int nbits, int inverse) { - int n, n4, i; + int n; // fixed32 alpha; - memset(s, 0, sizeof(*s)); n = 1 << nbits; //nbits ranges from 12 to 8 inclusive + s->nbits = nbits; s->n = n; - n4 = n >> 2; - s->tcos = tcosarray[12-nbits]; - s->tsin = tsinarray[12-nbits]; - for(i=0;i<n4;i++) - { - //fixed32 pi2 = fixmul32(0x20000, M_PI_F); - fixed32 ip = itofix32(i) + 0x2000; - ip = ip >> nbits; - //ip = fixdiv32(ip,itofix32(n)); // PJJ optimize - //alpha = fixmul32(TWO_M_PI_F, ip); - //s->tcos[i] = -fixcos32(alpha); //alpha between 0 and pi/2 - //s->tsin[i] = -fixsin32(alpha); - s->tsin[i] = - fsincos(ip<<16, &(s->tcos[i])); //I can't remember why this works, but it seems to agree for ~24 bits, maybe more! - s->tcos[i] *=-1; - } (&s->fft)->nbits = nbits-2; - (&s->fft)->inverse = inverse; return 0; @@ -76,8 +57,6 @@ void ff_imdct_calc(MDCTContext *s, fixed32 *input) { int k, n8, n4, n2, n, j,scale; - const fixed32 *tcos = s->tcos; - const fixed32 *tsin = s->tsin; const fixed32 *in1, *in2; FFTComplex *z1 = (FFTComplex *)output; FFTComplex *z2 = (FFTComplex *)input; @@ -96,19 +75,21 @@ void ff_imdct_calc(MDCTContext *s, for(k = 0; k < n4; k++) { - j=revtab0[k<<revtabshift]; - CMUL(&z1[j].re, &z1[j].im, *in2, *in1, tcos[k], tsin[k]); + int kshift = k<<revtabshift; + j=revtab0[kshift]; + CMUL(&z1[j].re, &z1[j].im, *in2, *in1, tcos0[kshift], tsin0[kshift]); in1 += 2; in2 -= 2; } - scale = fft_calc_unscaled(&s->fft, z1); + scale = fft_calc_unscaled(&s->fft, z1); /* post rotation + reordering */ for(k = 0; k < n4; k++) { - CMUL(&z2[k].re, &z2[k].im, (z1[k].re), (z1[k].im), tcos[k], tsin[k]); + int kshift = k<<revtabshift; + CMUL(&z2[k].re, &z2[k].im, (z1[k].re), (z1[k].im), tcos0[kshift], tsin0[kshift]); } for(k = 0; k < n8; k++) @@ -140,10 +121,6 @@ void ff_imdct_calc(MDCTContext *s, int mdct_init_global(void) { int i,j,m; - /* init MDCT */ - /*TODO: figure out how to fold this up into one array*/ - tcosarray[0] = tcos0; tcosarray[1] = tcos1; tcosarray[2] = tcos2; tcosarray[3] = tcos3;tcosarray[4] = tcos4; - tsinarray[0] = tsin0; tsinarray[1] = tsin1; tsinarray[2] = tsin2; tsinarray[3] = tsin3;tsinarray[4] = tsin4; /* init the MDCT bit reverse table here rather then in fft_init */ for(i=0;i<1024;i++) /*hard coded to a 2048 bit rotation*/ @@ -157,6 +134,21 @@ int mdct_init_global(void) revtab0[i]=m; } + for(i=0;i<1024;i++) + { + //fixed32 pi2 = fixmul32(0x20000, M_PI_F); + fixed32 ip = itofix32(i) + 0x2000; + ip = ip >> 12; + //ip = fixdiv32(ip,itofix32(n)); // PJJ optimize + //alpha = fixmul32(TWO_M_PI_F, ip); + //s->tcos[i] = -fixcos32(alpha); //alpha between 0 and pi/2 + //s->tsin[i] = -fixsin32(alpha); + + //I can't remember why this works, but it seems to agree for ~24 bits, maybe more! + tsin0[i] = - fsincos(ip<<16, &(tcos0[i])); + tcos0[i] *=-1; + } + fft_init_global(); return 0; |