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rockbox/apps/codecs/Tremor/mdct.c
Pedro Vasconcelos 0f10e898f0 Vorbis optimizations: allocation of PCM buffers in IRAM, avoiding copying. 
Slight code improvements to the MDCT functions.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6590 a1c6a512-1295-4272-9138-f99709370657
2005-06-06 23:01:51 +00:00

506 lines
14 KiB
C
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/********************************************************************
* *
* THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE. *
* *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
* *
* THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002 *
* BY THE Xiph.Org FOUNDATION http://www.xiph.org/ *
* *
********************************************************************
function: normalized modified discrete cosine transform
power of two length transform only [64 <= n ]
last mod: $Id$
Original algorithm adapted long ago from _The use of multirate filter
banks for coding of high quality digital audio_, by T. Sporer,
K. Brandenburg and B. Edler, collection of the European Signal
Processing Conference (EUSIPCO), Amsterdam, June 1992, Vol.1, pp
211-214
The below code implements an algorithm that no longer looks much like
that presented in the paper, but the basic structure remains if you
dig deep enough to see it.
This module DOES NOT INCLUDE code to generate/apply the window
function. Everybody has their own weird favorite including me... I
happen to like the properties of y=sin(.5PI*sin^2(x)), but others may
vehemently disagree.
********************************************************************/
#include "ivorbiscodec.h"
#include "os.h"
#include "misc.h"
#include "mdct.h"
#include "mdct_lookup.h"
/* 8 point butterfly (in place) */
STIN void mdct_butterfly_8(DATA_TYPE *x){
REG_TYPE r0 = x[4] + x[0];
REG_TYPE r1 = x[4] - x[0];
REG_TYPE r2 = x[5] + x[1];
REG_TYPE r3 = x[5] - x[1];
REG_TYPE r4 = x[6] + x[2];
REG_TYPE r5 = x[6] - x[2];
REG_TYPE r6 = x[7] + x[3];
REG_TYPE r7 = x[7] - x[3];
x[0] = r5 + r3;
x[1] = r7 - r1;
x[2] = r5 - r3;
x[3] = r7 + r1;
x[4] = r4 - r0;
x[5] = r6 - r2;
x[6] = r4 + r0;
x[7] = r6 + r2;
MB();
}
/* 16 point butterfly (in place, 4 register) */
STIN void mdct_butterfly_16(DATA_TYPE *x){
REG_TYPE r0, r1;
r0 = x[ 0] - x[ 8]; x[ 8] += x[ 0];
r1 = x[ 1] - x[ 9]; x[ 9] += x[ 1];
x[ 0] = MULT31((r0 + r1) , cPI2_8);
x[ 1] = MULT31((r1 - r0) , cPI2_8);
MB();
r0 = x[10] - x[ 2]; x[10] += x[ 2];
r1 = x[ 3] - x[11]; x[11] += x[ 3];
x[ 2] = r1; x[ 3] = r0;
MB();
r0 = x[12] - x[ 4]; x[12] += x[ 4];
r1 = x[13] - x[ 5]; x[13] += x[ 5];
x[ 4] = MULT31((r0 - r1) , cPI2_8);
x[ 5] = MULT31((r0 + r1) , cPI2_8);
MB();
r0 = x[14] - x[ 6]; x[14] += x[ 6];
r1 = x[15] - x[ 7]; x[15] += x[ 7];
x[ 6] = r0; x[ 7] = r1;
MB();
mdct_butterfly_8(x);
mdct_butterfly_8(x+8);
}
/* 32 point butterfly (in place, 4 register) */
STIN void mdct_butterfly_32(DATA_TYPE *x){
REG_TYPE r0, r1;
r0 = x[30] - x[14]; x[30] += x[14];
r1 = x[31] - x[15]; x[31] += x[15];
x[14] = r0; x[15] = r1;
MB();
r0 = x[28] - x[12]; x[28] += x[12];
r1 = x[29] - x[13]; x[29] += x[13];
XNPROD31( r0, r1, cPI1_8, cPI3_8, &x[12], &x[13] );
MB();
r0 = x[26] - x[10]; x[26] += x[10];
r1 = x[27] - x[11]; x[27] += x[11];
x[10] = MULT31((r0 - r1) , cPI2_8);
x[11] = MULT31((r0 + r1) , cPI2_8);
MB();
r0 = x[24] - x[ 8]; x[24] += x[ 8];
r1 = x[25] - x[ 9]; x[25] += x[ 9];
XNPROD31( r0, r1, cPI3_8, cPI1_8, &x[ 8], &x[ 9] );
MB();
r0 = x[22] - x[ 6]; x[22] += x[ 6];
r1 = x[ 7] - x[23]; x[23] += x[ 7];
x[ 6] = r1; x[ 7] = r0;
MB();
r0 = x[ 4] - x[20]; x[20] += x[ 4];
r1 = x[ 5] - x[21]; x[21] += x[ 5];
XPROD31 ( r0, r1, cPI3_8, cPI1_8, &x[ 4], &x[ 5] );
MB();
r0 = x[ 2] - x[18]; x[18] += x[ 2];
r1 = x[ 3] - x[19]; x[19] += x[ 3];
x[ 2] = MULT31((r1 + r0) , cPI2_8);
x[ 3] = MULT31((r1 - r0) , cPI2_8);
MB();
r0 = x[ 0] - x[16]; x[16] += x[ 0];
r1 = x[ 1] - x[17]; x[17] += x[ 1];
XPROD31 ( r0, r1, cPI1_8, cPI3_8, &x[ 0], &x[ 1] );
MB();
mdct_butterfly_16(x);
mdct_butterfly_16(x+16);
}
/* N/stage point generic N stage butterfly (in place, 4 register) */
void mdct_butterfly_generic(DATA_TYPE *x,int points, int step){
LOOKUP_T *T = sincos_lookup0;
DATA_TYPE *x1 = x + points - 8;
DATA_TYPE *x2 = x + (points>>1) - 8;
REG_TYPE r0;
REG_TYPE r1;
REG_TYPE r2;
REG_TYPE r3;
do{
r0 = x1[6] - x2[6]; x1[6] += x2[6];
r1 = x2[7] - x1[7]; x1[7] += x2[7];
r2 = x1[4] - x2[4]; x1[4] += x2[4];
r3 = x2[5] - x1[5]; x1[5] += x2[5];
XPROD31( r1, r0, T[0], T[1], &x2[6], &x2[7] ); T+=step;
XPROD31( r3, r2, T[0], T[1], &x2[4], &x2[5] ); T+=step;
r0 = x1[2] - x2[2]; x1[2] += x2[2];
r1 = x2[3] - x1[3]; x1[3] += x2[3];
r2 = x1[0] - x2[0]; x1[0] += x2[0];
r3 = x2[1] - x1[1]; x1[1] += x2[1];
XPROD31( r1, r0, T[0], T[1], &x2[2], &x2[3] ); T+=step;
XPROD31( r3, r2, T[0], T[1], &x2[0], &x2[1] ); T+=step;
x1-=8; x2-=8;
}while(T<sincos_lookup0+1024);
do{
r0 = x1[6] - x2[6]; x1[6] += x2[6];
r1 = x1[7] - x2[7]; x1[7] += x2[7];
r2 = x1[4] - x2[4]; x1[4] += x2[4];
r3 = x1[5] - x2[5]; x1[5] += x2[5];
XNPROD31( r0, r1, T[0], T[1], &x2[6], &x2[7] ); T-=step;
XNPROD31( r2, r3, T[0], T[1], &x2[4], &x2[5] ); T-=step;
r0 = x1[2] - x2[2]; x1[2] += x2[2];
r1 = x1[3] - x2[3]; x1[3] += x2[3];
r2 = x1[0] - x2[0]; x1[0] += x2[0];
r3 = x1[1] - x2[1]; x1[1] += x2[1];
XNPROD31( r0, r1, T[0], T[1], &x2[2], &x2[3] ); T-=step;
XNPROD31( r2, r3, T[0], T[1], &x2[0], &x2[1] ); T-=step;
x1-=8; x2-=8;
}while(T>sincos_lookup0);
do{
r0 = x2[6] - x1[6]; x1[6] += x2[6];
r1 = x2[7] - x1[7]; x1[7] += x2[7];
r2 = x2[4] - x1[4]; x1[4] += x2[4];
r3 = x2[5] - x1[5]; x1[5] += x2[5];
XPROD31( r0, r1, T[0], T[1], &x2[6], &x2[7] ); T+=step;
XPROD31( r2, r3, T[0], T[1], &x2[4], &x2[5] ); T+=step;
r0 = x2[2] - x1[2]; x1[2] += x2[2];
r1 = x2[3] - x1[3]; x1[3] += x2[3];
r2 = x2[0] - x1[0]; x1[0] += x2[0];
r3 = x2[1] - x1[1]; x1[1] += x2[1];
XPROD31( r0, r1, T[0], T[1], &x2[2], &x2[3] ); T+=step;
XPROD31( r2, r3, T[0], T[1], &x2[0], &x2[1] ); T+=step;
x1-=8; x2-=8;
}while(T<sincos_lookup0+1024);
do{
r0 = x1[6] - x2[6]; x1[6] += x2[6];
r1 = x2[7] - x1[7]; x1[7] += x2[7];
r2 = x1[4] - x2[4]; x1[4] += x2[4];
r3 = x2[5] - x1[5]; x1[5] += x2[5];
XNPROD31( r1, r0, T[0], T[1], &x2[6], &x2[7] ); T-=step;
XNPROD31( r3, r2, T[0], T[1], &x2[4], &x2[5] ); T-=step;
r0 = x1[2] - x2[2]; x1[2] += x2[2];
r1 = x2[3] - x1[3]; x1[3] += x2[3];
r2 = x1[0] - x2[0]; x1[0] += x2[0];
r3 = x2[1] - x1[1]; x1[1] += x2[1];
XNPROD31( r1, r0, T[0], T[1], &x2[2], &x2[3] ); T-=step;
XNPROD31( r3, r2, T[0], T[1], &x2[0], &x2[1] ); T-=step;
x1-=8; x2-=8;
}while(T>sincos_lookup0);
}
STIN void mdct_butterflies(DATA_TYPE *x,int points,int shift) {
int stages=8-shift;
int i,j;
for(i=0;--stages>0;i++){
for(j=0;j<(1<<i);j++)
mdct_butterfly_generic(x+(points>>i)*j,points>>i,4<<(i+shift));
}
for(j=0;j<points;j+=32)
mdct_butterfly_32(x+j);
}
static const unsigned char bitrev[16] IDATA_ATTR =
{0,8,4,12,2,10,6,14,1,9,5,13,3,11,7,15};
STIN int bitrev12(int x){
return bitrev[x>>8]|(bitrev[(x&0x0f0)>>4]<<4)|(((int)bitrev[x&0x00f])<<8);
}
STIN void mdct_bitreverse(DATA_TYPE *x,int n,int step,int shift) {
int bit = 0;
DATA_TYPE *w0 = x;
DATA_TYPE *w1 = x = w0+(n>>1);
LOOKUP_T *T = (step>=4)?(sincos_lookup0+(step>>1)):sincos_lookup1;
LOOKUP_T *Ttop = T+1024;
REG_TYPE r2;
do{
REG_TYPE r3 = bitrev12(bit++);
DATA_TYPE *x0 = x + ((r3 ^ 0xfff)>>shift) -1;
DATA_TYPE *x1 = x + (r3>>shift);
REG_TYPE r0 = x0[0] + x1[0];
REG_TYPE r1 = x1[1] - x0[1];
XPROD32( r0, r1, T[1], T[0], r2, r3 ); T+=step;
w1 -= 4;
r0 = (x0[1] + x1[1])>>1;
r1 = (x0[0] - x1[0])>>1;
w0[0] = r0 + r2;
w0[1] = r1 + r3;
w1[2] = r0 - r2;
w1[3] = r3 - r1;
r3 = bitrev12(bit++);
x0 = x + ((r3 ^ 0xfff)>>shift) -1;
x1 = x + (r3>>shift);
r0 = x0[0] + x1[0];
r1 = x1[1] - x0[1];
XPROD32( r0, r1, T[1], T[0], r2, r3 ); T+=step;
r0 = (x0[1] + x1[1])>>1;
r1 = (x0[0] - x1[0])>>1;
w0[2] = r0 + r2;
w0[3] = r1 + r3;
w1[0] = r0 - r2;
w1[1] = r3 - r1;
w0 += 4;
}while(T<Ttop);
do{
REG_TYPE r3 = bitrev12(bit++);
DATA_TYPE *x0 = x + ((r3 ^ 0xfff)>>shift) -1;
DATA_TYPE *x1 = x + (r3>>shift);
REG_TYPE r0 = x0[0] + x1[0];
REG_TYPE r1 = x1[1] - x0[1];
T-=step; XPROD32( r0, r1, T[0], T[1], r2, r3 );
w1 -= 4;
r0 = (x0[1] + x1[1])>>1;
r1 = (x0[0] - x1[0])>>1;
w0[0] = r0 + r2;
w0[1] = r1 + r3;
w1[2] = r0 - r2;
w1[3] = r3 - r1;
r3 = bitrev12(bit++);
x0 = x + ((r3 ^ 0xfff)>>shift) -1;
x1 = x + (r3>>shift);
r0 = x0[0] + x1[0];
r1 = x1[1] - x0[1];
T-=step; XPROD32( r0, r1, T[0], T[1], r2, r3 );
r0 = (x0[1] + x1[1])>>1;
r1 = (x0[0] - x1[0])>>1;
w0[2] = r0 + r2;
w0[3] = r1 + r3;
w1[0] = r0 - r2;
w1[1] = r3 - r1;
w0 += 4;
}while(w0<w1);
}
void mdct_backward(int n, DATA_TYPE *in, DATA_TYPE *out) {
int n2=n>>1;
int n4=n>>2;
DATA_TYPE *iX;
DATA_TYPE *oX;
LOOKUP_T *T;
LOOKUP_T *V;
int shift;
int step;
#if CONFIG_CPU == MCF5249
mcf5249_init_mac(); /* should be redundant */
#endif
for (shift=6;!(n&(1<<shift));shift++);
shift=13-shift;
step=2<<shift;
/* rotate */
iX = in+n2-7;
oX = out+n2+n4;
T = sincos_lookup0;
do{
oX-=4;
XPROD31( iX[4], iX[6], T[0], T[1], &oX[2], &oX[3] ); T+=step;
XPROD31( iX[0], iX[2], T[0], T[1], &oX[0], &oX[1] ); T+=step;
iX-=8;
}while(iX>=in+n4);
do{
oX-=4;
XPROD31( iX[4], iX[6], T[1], T[0], &oX[2], &oX[3] ); T-=step;
XPROD31( iX[0], iX[2], T[1], T[0], &oX[0], &oX[1] ); T-=step;
iX-=8;
}while(iX>=in);
iX = in+n2-8;
oX = out+n2+n4;
T = sincos_lookup0;
do{
T+=step; XNPROD31( iX[6], iX[4], T[0], T[1], &oX[0], &oX[1] );
T+=step; XNPROD31( iX[2], iX[0], T[0], T[1], &oX[2], &oX[3] );
iX-=8;
oX+=4;
}while(iX>=in+n4);
do{
T-=step; XNPROD31( iX[6], iX[4], T[1], T[0], &oX[0], &oX[1] );
T-=step; XNPROD31( iX[2], iX[0], T[1], T[0], &oX[2], &oX[3] );
iX-=8;
oX+=4;
}while(iX>=in);
mdct_butterflies(out+n2,n2,shift);
mdct_bitreverse(out,n,step,shift);
/* rotate + window */
step>>=2;
{
DATA_TYPE *oX1=out+n2+n4;
DATA_TYPE *oX2=out+n2+n4;
DATA_TYPE *iX =out;
switch(step) {
default: {
T=(step>=4)?(sincos_lookup0+(step>>1)):sincos_lookup1;
do{
oX1-=4;
XPROD31( iX[0], -iX[1], T[0], T[1], &oX1[3], &oX2[0] ); T+=step;
XPROD31( iX[2], -iX[3], T[0], T[1], &oX1[2], &oX2[1] ); T+=step;
XPROD31( iX[4], -iX[5], T[0], T[1], &oX1[1], &oX2[2] ); T+=step;
XPROD31( iX[6], -iX[7], T[0], T[1], &oX1[0], &oX2[3] ); T+=step;
oX2+=4;
iX+=8;
}while(iX<oX1);
break;
}
case 1: {
/* linear interpolation between table values: offset=0.5, step=1 */
REG_TYPE t0,t1,v0,v1;
T = sincos_lookup0;
V = sincos_lookup1;
t0 = (*T++)>>1;
t1 = (*T++)>>1;
do{
oX1-=4;
t0 += (v0 = (*V++)>>1);
t1 += (v1 = (*V++)>>1);
XPROD31( iX[0], -iX[1], t0, t1, &oX1[3], &oX2[0] );
v0 += (t0 = (*T++)>>1);
v1 += (t1 = (*T++)>>1);
XPROD31( iX[2], -iX[3], v0, v1, &oX1[2], &oX2[1] );
t0 += (v0 = (*V++)>>1);
t1 += (v1 = (*V++)>>1);
XPROD31( iX[4], -iX[5], t0, t1, &oX1[1], &oX2[2] );
v0 += (t0 = (*T++)>>1);
v1 += (t1 = (*T++)>>1);
XPROD31( iX[6], -iX[7], v0, v1, &oX1[0], &oX2[3] );
oX2+=4;
iX+=8;
}while(iX<oX1);
break;
}
case 0: {
/* linear interpolation between table values: offset=0.25, step=0.5 */
REG_TYPE t0,t1,v0,v1,q0,q1;
T = sincos_lookup0;
V = sincos_lookup1;
t0 = *T++;
t1 = *T++;
do{
oX1-=4;
v0 = *V++;
v1 = *V++;
t0 += (q0 = (v0-t0)>>2);
t1 += (q1 = (v1-t1)>>2);
XPROD31( iX[0], -iX[1], t0, t1, &oX1[3], &oX2[0] );
t0 = v0-q0;
t1 = v1-q1;
XPROD31( iX[2], -iX[3], t0, t1, &oX1[2], &oX2[1] );
t0 = *T++;
t1 = *T++;
v0 += (q0 = (t0-v0)>>2);
v1 += (q1 = (t1-v1)>>2);
XPROD31( iX[4], -iX[5], v0, v1, &oX1[1], &oX2[2] );
v0 = t0-q0;
v1 = t1-q1;
XPROD31( iX[6], -iX[7], v0, v1, &oX1[0], &oX2[3] );
oX2+=4;
iX+=8;
}while(iX<oX1);
break;
}
}
iX=out+n2+n4;
oX1=out+n4;
oX2=oX1;
do{
oX1-=4;
iX-=4;
oX2[0] = -(oX1[3] = iX[3]);
oX2[1] = -(oX1[2] = iX[2]);
oX2[2] = -(oX1[1] = iX[1]);
oX2[3] = -(oX1[0] = iX[0]);
oX2+=4;
}while(oX2<iX);
iX=out+n2+n4;
oX1=out+n2+n4;
oX2=out+n2;
do{
oX1-=4;
oX1[0]= iX[3];
oX1[1]= iX[2];
oX1[2]= iX[1];
oX1[3]= iX[0];
iX+=4;
}while(oX1>oX2);
}
}
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