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-/********************************************************************
- * *
- * THIS FILE IS PART OF THE OggVorbis SOFTWARE 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 SOURCE CODE IS (C) COPYRIGHT 1994-2009 *
- * by the Xiph.Org Foundation http://www.xiph.org/ *
- * *
- ********************************************************************
-
- function: normalized modified discrete cosine transform
- power of two length transform only [64 <= n ]
-
- 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.
-
- ********************************************************************/
-
-/* this can also be run as an integer transform by uncommenting a
- define in mdct.h; the integerization is a first pass and although
- it's likely stable for Vorbis, the dynamic range is constrained and
- roundoff isn't done (so it's noisy). Consider it functional, but
- only a starting point. There's no point on a machine with an FPU */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <math.h>
-#include "vorbis/codec.h"
-#include "mdct.h"
-#include "os.h"
-#include "misc.h"
-
-/* build lookups for trig functions; also pre-figure scaling and
- some window function algebra. */
-
-void mdct_init(mdct_lookup *lookup,int n){
- int *bitrev=_ogg_malloc(sizeof(*bitrev)*(n/4));
- DATA_TYPE *T=_ogg_malloc(sizeof(*T)*(n+n/4));
-
- int i;
- int n2=n>>1;
- int log2n=lookup->log2n=rint(log((float)n)/log(2.f));
- lookup->n=n;
- lookup->trig=T;
- lookup->bitrev=bitrev;
-
-/* trig lookups... */
-
- for(i=0;i<n/4;i++){
- T[i*2]=FLOAT_CONV(cos((M_PI/n)*(4*i)));
- T[i*2+1]=FLOAT_CONV(-sin((M_PI/n)*(4*i)));
- T[n2+i*2]=FLOAT_CONV(cos((M_PI/(2*n))*(2*i+1)));
- T[n2+i*2+1]=FLOAT_CONV(sin((M_PI/(2*n))*(2*i+1)));
- }
- for(i=0;i<n/8;i++){
- T[n+i*2]=FLOAT_CONV(cos((M_PI/n)*(4*i+2))*.5);
- T[n+i*2+1]=FLOAT_CONV(-sin((M_PI/n)*(4*i+2))*.5);
- }
-
- /* bitreverse lookup... */
-
- {
- int mask=(1<<(log2n-1))-1,i,j;
- int msb=1<<(log2n-2);
- for(i=0;i<n/8;i++){
- int acc=0;
- for(j=0;msb>>j;j++)
- if((msb>>j)&i)acc|=1<<j;
- bitrev[i*2]=((~acc)&mask)-1;
- bitrev[i*2+1]=acc;
-
- }
- }
- lookup->scale=FLOAT_CONV(4.f/n);
-}
-
-/* 8 point butterfly (in place, 4 register) */
-STIN void mdct_butterfly_8(DATA_TYPE *x){
- REG_TYPE r0 = x[6] + x[2];
- REG_TYPE r1 = x[6] - x[2];
- REG_TYPE r2 = x[4] + x[0];
- REG_TYPE r3 = x[4] - x[0];
-
- x[6] = r0 + r2;
- x[4] = r0 - r2;
-
- r0 = x[5] - x[1];
- r2 = x[7] - x[3];
- x[0] = r1 + r0;
- x[2] = r1 - r0;
-
- r0 = x[5] + x[1];
- r1 = x[7] + x[3];
- x[3] = r2 + r3;
- x[1] = r2 - r3;
- x[7] = r1 + r0;
- x[5] = r1 - r0;
-
-}
-
-/* 16 point butterfly (in place, 4 register) */
-STIN void mdct_butterfly_16(DATA_TYPE *x){
- REG_TYPE r0 = x[1] - x[9];
- REG_TYPE r1 = x[0] - x[8];
-
- x[8] += x[0];
- x[9] += x[1];
- x[0] = MULT_NORM((r0 + r1) * cPI2_8);
- x[1] = MULT_NORM((r0 - r1) * cPI2_8);
-
- r0 = x[3] - x[11];
- r1 = x[10] - x[2];
- x[10] += x[2];
- x[11] += x[3];
- x[2] = r0;
- x[3] = r1;
-
- r0 = x[12] - x[4];
- r1 = x[13] - x[5];
- x[12] += x[4];
- x[13] += x[5];
- x[4] = MULT_NORM((r0 - r1) * cPI2_8);
- x[5] = MULT_NORM((r0 + r1) * cPI2_8);
-
- r0 = x[14] - x[6];
- r1 = x[15] - x[7];
- x[14] += x[6];
- x[15] += x[7];
- x[6] = r0;
- x[7] = r1;
-
- 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 = x[30] - x[14];
- REG_TYPE r1 = x[31] - x[15];
-
- x[30] += x[14];
- x[31] += x[15];
- x[14] = r0;
- x[15] = r1;
-
- r0 = x[28] - x[12];
- r1 = x[29] - x[13];
- x[28] += x[12];
- x[29] += x[13];
- x[12] = MULT_NORM( r0 * cPI1_8 - r1 * cPI3_8 );
- x[13] = MULT_NORM( r0 * cPI3_8 + r1 * cPI1_8 );
-
- r0 = x[26] - x[10];
- r1 = x[27] - x[11];
- x[26] += x[10];
- x[27] += x[11];
- x[10] = MULT_NORM(( r0 - r1 ) * cPI2_8);
- x[11] = MULT_NORM(( r0 + r1 ) * cPI2_8);
-
- r0 = x[24] - x[8];
- r1 = x[25] - x[9];
- x[24] += x[8];
- x[25] += x[9];
- x[8] = MULT_NORM( r0 * cPI3_8 - r1 * cPI1_8 );
- x[9] = MULT_NORM( r1 * cPI3_8 + r0 * cPI1_8 );
-
- r0 = x[22] - x[6];
- r1 = x[7] - x[23];
- x[22] += x[6];
- x[23] += x[7];
- x[6] = r1;
- x[7] = r0;
-
- r0 = x[4] - x[20];
- r1 = x[5] - x[21];
- x[20] += x[4];
- x[21] += x[5];
- x[4] = MULT_NORM( r1 * cPI1_8 + r0 * cPI3_8 );
- x[5] = MULT_NORM( r1 * cPI3_8 - r0 * cPI1_8 );
-
- r0 = x[2] - x[18];
- r1 = x[3] - x[19];
- x[18] += x[2];
- x[19] += x[3];
- x[2] = MULT_NORM(( r1 + r0 ) * cPI2_8);
- x[3] = MULT_NORM(( r1 - r0 ) * cPI2_8);
-
- r0 = x[0] - x[16];
- r1 = x[1] - x[17];
- x[16] += x[0];
- x[17] += x[1];
- x[0] = MULT_NORM( r1 * cPI3_8 + r0 * cPI1_8 );
- x[1] = MULT_NORM( r1 * cPI1_8 - r0 * cPI3_8 );
-
- mdct_butterfly_16(x);
- mdct_butterfly_16(x+16);
-
-}
-
-/* N point first stage butterfly (in place, 2 register) */
-STIN void mdct_butterfly_first(DATA_TYPE *T,
- DATA_TYPE *x,
- int points){
-
- DATA_TYPE *x1 = x + points - 8;
- DATA_TYPE *x2 = x + (points>>1) - 8;
- REG_TYPE r0;
- REG_TYPE r1;
-
- do{
-
- r0 = x1[6] - x2[6];
- r1 = x1[7] - x2[7];
- x1[6] += x2[6];
- x1[7] += x2[7];
- x2[6] = MULT_NORM(r1 * T[1] + r0 * T[0]);
- x2[7] = MULT_NORM(r1 * T[0] - r0 * T[1]);
-
- r0 = x1[4] - x2[4];
- r1 = x1[5] - x2[5];
- x1[4] += x2[4];
- x1[5] += x2[5];
- x2[4] = MULT_NORM(r1 * T[5] + r0 * T[4]);
- x2[5] = MULT_NORM(r1 * T[4] - r0 * T[5]);
-
- r0 = x1[2] - x2[2];
- r1 = x1[3] - x2[3];
- x1[2] += x2[2];
- x1[3] += x2[3];
- x2[2] = MULT_NORM(r1 * T[9] + r0 * T[8]);
- x2[3] = MULT_NORM(r1 * T[8] - r0 * T[9]);
-
- r0 = x1[0] - x2[0];
- r1 = x1[1] - x2[1];
- x1[0] += x2[0];
- x1[1] += x2[1];
- x2[0] = MULT_NORM(r1 * T[13] + r0 * T[12]);
- x2[1] = MULT_NORM(r1 * T[12] - r0 * T[13]);
-
- x1-=8;
- x2-=8;
- T+=16;
-
- }while(x2>=x);
-}
-
-/* N/stage point generic N stage butterfly (in place, 2 register) */
-STIN void mdct_butterfly_generic(DATA_TYPE *T,
- DATA_TYPE *x,
- int points,
- int trigint){
-
- DATA_TYPE *x1 = x + points - 8;
- DATA_TYPE *x2 = x + (points>>1) - 8;
- REG_TYPE r0;
- REG_TYPE r1;
-
- do{
-
- r0 = x1[6] - x2[6];
- r1 = x1[7] - x2[7];
- x1[6] += x2[6];
- x1[7] += x2[7];
- x2[6] = MULT_NORM(r1 * T[1] + r0 * T[0]);
- x2[7] = MULT_NORM(r1 * T[0] - r0 * T[1]);
-
- T+=trigint;
-
- r0 = x1[4] - x2[4];
- r1 = x1[5] - x2[5];
- x1[4] += x2[4];
- x1[5] += x2[5];
- x2[4] = MULT_NORM(r1 * T[1] + r0 * T[0]);
- x2[5] = MULT_NORM(r1 * T[0] - r0 * T[1]);
-
- T+=trigint;
-
- r0 = x1[2] - x2[2];
- r1 = x1[3] - x2[3];
- x1[2] += x2[2];
- x1[3] += x2[3];
- x2[2] = MULT_NORM(r1 * T[1] + r0 * T[0]);
- x2[3] = MULT_NORM(r1 * T[0] - r0 * T[1]);
-
- T+=trigint;
-
- r0 = x1[0] - x2[0];
- r1 = x1[1] - x2[1];
- x1[0] += x2[0];
- x1[1] += x2[1];
- x2[0] = MULT_NORM(r1 * T[1] + r0 * T[0]);
- x2[1] = MULT_NORM(r1 * T[0] - r0 * T[1]);
-
- T+=trigint;
- x1-=8;
- x2-=8;
-
- }while(x2>=x);
-}
-
-STIN void mdct_butterflies(mdct_lookup *init,
- DATA_TYPE *x,
- int points){
-
- DATA_TYPE *T=init->trig;
- int stages=init->log2n-5;
- int i,j;
-
- if(--stages>0){
- mdct_butterfly_first(T,x,points);
- }
-
- for(i=1;--stages>0;i++){
- for(j=0;j<(1<<i);j++)
- mdct_butterfly_generic(T,x+(points>>i)*j,points>>i,4<<i);
- }
-
- for(j=0;j<points;j+=32)
- mdct_butterfly_32(x+j);
-
-}
-
-void mdct_clear(mdct_lookup *l){
- if(l){
- if(l->trig)_ogg_free(l->trig);
- if(l->bitrev)_ogg_free(l->bitrev);
- memset(l,0,sizeof(*l));
- }
-}
-
-STIN void mdct_bitreverse(mdct_lookup *init,
- DATA_TYPE *x){
- int n = init->n;
- int *bit = init->bitrev;
- DATA_TYPE *w0 = x;
- DATA_TYPE *w1 = x = w0+(n>>1);
- DATA_TYPE *T = init->trig+n;
-
- do{
- DATA_TYPE *x0 = x+bit[0];
- DATA_TYPE *x1 = x+bit[1];
-
- REG_TYPE r0 = x0[1] - x1[1];
- REG_TYPE r1 = x0[0] + x1[0];
- REG_TYPE r2 = MULT_NORM(r1 * T[0] + r0 * T[1]);
- REG_TYPE r3 = MULT_NORM(r1 * T[1] - r0 * T[0]);
-
- w1 -= 4;
-
- r0 = HALVE(x0[1] + x1[1]);
- r1 = HALVE(x0[0] - x1[0]);
-
- w0[0] = r0 + r2;
- w1[2] = r0 - r2;
- w0[1] = r1 + r3;
- w1[3] = r3 - r1;
-
- x0 = x+bit[2];
- x1 = x+bit[3];
-
- r0 = x0[1] - x1[1];
- r1 = x0[0] + x1[0];
- r2 = MULT_NORM(r1 * T[2] + r0 * T[3]);
- r3 = MULT_NORM(r1 * T[3] - r0 * T[2]);
-
- r0 = HALVE(x0[1] + x1[1]);
- r1 = HALVE(x0[0] - x1[0]);
-
- w0[2] = r0 + r2;
- w1[0] = r0 - r2;
- w0[3] = r1 + r3;
- w1[1] = r3 - r1;
-
- T += 4;
- bit += 4;
- w0 += 4;
-
- }while(w0<w1);
-}
-
-void mdct_backward(mdct_lookup *init, DATA_TYPE *in, DATA_TYPE *out){
- int n=init->n;
- int n2=n>>1;
- int n4=n>>2;
-
- /* rotate */
-
- DATA_TYPE *iX = in+n2-7;
- DATA_TYPE *oX = out+n2+n4;
- DATA_TYPE *T = init->trig+n4;
-
- do{
- oX -= 4;
- oX[0] = MULT_NORM(-iX[2] * T[3] - iX[0] * T[2]);
- oX[1] = MULT_NORM (iX[0] * T[3] - iX[2] * T[2]);
- oX[2] = MULT_NORM(-iX[6] * T[1] - iX[4] * T[0]);
- oX[3] = MULT_NORM (iX[4] * T[1] - iX[6] * T[0]);
- iX -= 8;
- T += 4;
- }while(iX>=in);
-
- iX = in+n2-8;
- oX = out+n2+n4;
- T = init->trig+n4;
-
- do{
- T -= 4;
- oX[0] = MULT_NORM (iX[4] * T[3] + iX[6] * T[2]);
- oX[1] = MULT_NORM (iX[4] * T[2] - iX[6] * T[3]);
- oX[2] = MULT_NORM (iX[0] * T[1] + iX[2] * T[0]);
- oX[3] = MULT_NORM (iX[0] * T[0] - iX[2] * T[1]);
- iX -= 8;
- oX += 4;
- }while(iX>=in);
-
- mdct_butterflies(init,out+n2,n2);
- mdct_bitreverse(init,out);
-
- /* roatate + window */
-
- {
- DATA_TYPE *oX1=out+n2+n4;
- DATA_TYPE *oX2=out+n2+n4;
- DATA_TYPE *iX =out;
- T =init->trig+n2;
-
- do{
- oX1-=4;
-
- oX1[3] = MULT_NORM (iX[0] * T[1] - iX[1] * T[0]);
- oX2[0] = -MULT_NORM (iX[0] * T[0] + iX[1] * T[1]);
-
- oX1[2] = MULT_NORM (iX[2] * T[3] - iX[3] * T[2]);
- oX2[1] = -MULT_NORM (iX[2] * T[2] + iX[3] * T[3]);
-
- oX1[1] = MULT_NORM (iX[4] * T[5] - iX[5] * T[4]);
- oX2[2] = -MULT_NORM (iX[4] * T[4] + iX[5] * T[5]);
-
- oX1[0] = MULT_NORM (iX[6] * T[7] - iX[7] * T[6]);
- oX2[3] = -MULT_NORM (iX[6] * T[6] + iX[7] * T[7]);
-
- oX2+=4;
- iX += 8;
- T += 8;
- }while(iX<oX1);
-
- 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);
- }
-}
-
-void mdct_forward(mdct_lookup *init, DATA_TYPE *in, DATA_TYPE *out){
- int n=init->n;
- int n2=n>>1;
- int n4=n>>2;
- int n8=n>>3;
- DATA_TYPE *w=alloca(n*sizeof(*w)); /* forward needs working space */
- DATA_TYPE *w2=w+n2;
-
- /* rotate */
-
- /* window + rotate + step 1 */
-
- REG_TYPE r0;
- REG_TYPE r1;
- DATA_TYPE *x0=in+n2+n4;
- DATA_TYPE *x1=x0+1;
- DATA_TYPE *T=init->trig+n2;
-
- int i=0;
-
- for(i=0;i<n8;i+=2){
- x0 -=4;
- T-=2;
- r0= x0[2] + x1[0];
- r1= x0[0] + x1[2];
- w2[i]= MULT_NORM(r1*T[1] + r0*T[0]);
- w2[i+1]= MULT_NORM(r1*T[0] - r0*T[1]);
- x1 +=4;
- }
-
- x1=in+1;
-
- for(;i<n2-n8;i+=2){
- T-=2;
- x0 -=4;
- r0= x0[2] - x1[0];
- r1= x0[0] - x1[2];
- w2[i]= MULT_NORM(r1*T[1] + r0*T[0]);
- w2[i+1]= MULT_NORM(r1*T[0] - r0*T[1]);
- x1 +=4;
- }
-
- x0=in+n;
-
- for(;i<n2;i+=2){
- T-=2;
- x0 -=4;
- r0= -x0[2] - x1[0];
- r1= -x0[0] - x1[2];
- w2[i]= MULT_NORM(r1*T[1] + r0*T[0]);
- w2[i+1]= MULT_NORM(r1*T[0] - r0*T[1]);
- x1 +=4;
- }
-
-
- mdct_butterflies(init,w+n2,n2);
- mdct_bitreverse(init,w);
-
- /* roatate + window */
-
- T=init->trig+n2;
- x0=out+n2;
-
- for(i=0;i<n4;i++){
- x0--;
- out[i] =MULT_NORM((w[0]*T[0]+w[1]*T[1])*init->scale);
- x0[0] =MULT_NORM((w[0]*T[1]-w[1]*T[0])*init->scale);
- w+=2;
- T+=2;
- }
-}
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