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DECODEI3.C
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C/C++ Source or Header
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1997-04-10
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9KB
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339 lines
/*
* Mpeg Layer-1,2,3 audio decoder
* ------------------------------
* copyright (c) 1995,1996,1997 by Michael Hipp, All rights reserved.
* See also 'README'
* slighlty optimized for machines without autoincrement/decrement
*
*/
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "mpg123.h"
static void tr(real *here,real *samples);
#define WRITE_SAMPLE(samples,sum,clip) \
if( (sum) > 32767.0) { *(samples) = 0x7fff; (clip)++; } \
else if( (sum) < -32768.0) { *(samples) = -0x8000; (clip)++; } \
else { *(samples) = sum; }
int synth_1to1(real *bandPtr,int channel,short *samples)
{
static real buf1[0x200],buf0[0x200];
static int boc[2]={1,1};
static real *buffs[2] = { buf0,buf1 };
static const int step = 2;
int bo;
int clip = 0;
real *buf = buffs[channel];
samples += channel;
bo = boc[channel];
bo--;
bo &= 0xf;
boc[channel] = bo;
tr(buf+(bo<<5),bandPtr); /* writes values from buf[0] to buf[3f] */
if(bo & 0x1) {
register int j;
register real *window,*b0,*b1,sum;
window = decwin + 16 - bo;
b0 = buf + 15;
b1 = buf + 15;
for (j=16;j;j--,b0++,b1--,window+=32,samples+=step)
{
sum = window[0] * b0[0x000];
sum -= window[1] * b1[0x020];
sum += window[2] * b0[0x040];
sum -= window[3] * b1[0x060];
sum += window[4] * b0[0x080];
sum -= window[5] * b1[0x0a0];
sum += window[6] * b0[0x0c0];
sum -= window[7] * b1[0x0e0];
sum += window[8] * b0[0x100];
sum -= window[9] * b1[0x120];
sum += window[10] * b0[0x140];
sum -= window[11] * b1[0x160];
sum += window[12] * b0[0x180];
sum -= window[13] * b1[0x1a0];
sum += window[14] * b0[0x1c0];
sum -= window[15] * b1[0x1e0];
WRITE_SAMPLE(samples,sum,clip);
}
{
sum = window[0] * b0[0x000];
sum += window[2] * b0[0x040];
sum += window[4] * b0[0x080];
sum += window[6] * b0[0x0c0];
sum += window[8] * b0[0x100];
sum += window[10] * b0[0x140];
sum += window[12] * b0[0x180];
sum += window[14] * b0[0x1c0];
WRITE_SAMPLE(samples,sum,clip);
b0--,b1++,window-=32,samples+=step;
}
window += bo<<1;
for (j=15;j;j--,b0--,b1++,window-=32,samples+=step)
{
sum = -window[-1] * b0[0x000];
sum -= window[-2] * b1[0x020];
sum -= window[-3] * b0[0x040];
sum -= window[-4] * b1[0x060];
sum -= window[-5] * b0[0x080];
sum -= window[-6] * b1[0x0a0];
sum -= window[-7] * b0[0x0c0];
sum -= window[-8] * b1[0x0e0];
sum -= window[-9] * b0[0x100];
sum -= window[-10] * b1[0x120];
sum -= window[-11] * b0[0x140];
sum -= window[-12] * b1[0x160];
sum -= window[-13] * b0[0x180];
sum -= window[-14] * b1[0x1a0];
sum -= window[-15] * b0[0x1c0];
sum -= window[-16] * b1[0x1e0];
WRITE_SAMPLE(samples,sum,clip);
}
}
else {
register int j;
register real *window,*b0,*b1,sum;
window = decwin + 16 - bo;
b0 = buf + 15;
b1 = buf + 15;
for (j=16;j;j--,b0--,b1++,window+=32,samples+=step)
{
sum = -window[0] * b0[0x000];
sum += window[1] * b1[0x020];
sum -= window[2] * b0[0x040];
sum += window[3] * b1[0x060];
sum -= window[4] * b0[0x080];
sum += window[5] * b1[0x0a0];
sum -= window[6] * b0[0x0c0];
sum += window[7] * b1[0x0e0];
sum -= window[8] * b0[0x100];
sum += window[9] * b1[0x120];
sum -= window[10] * b0[0x140];
sum += window[11] * b1[0x160];
sum -= window[12] * b0[0x180];
sum += window[13] * b1[0x1a0];
sum -= window[14] * b0[0x1c0];
sum += window[15] * b1[0x1e0];
WRITE_SAMPLE(samples,sum,clip);
}
{
sum = window[1] * b1[0x020];
sum += window[3] * b1[0x060];
sum += window[5] * b1[0x0a0];
sum += window[7] * b1[0x0e0];
sum += window[9] * b1[0x120];
sum += window[11] * b1[0x160];
sum += window[13] * b1[0x1a0];
sum += window[15] * b1[0x1e0];
WRITE_SAMPLE(samples,sum,clip);
b0++,b1--,window-=32,samples+=step;
}
window += bo<<1;
for (j=15;j;j--,b0++,b1--,window-=32,samples+=step)
{
sum = -window[-1] * b0[0x000];
sum -= window[-2] * b1[0x020];
sum -= window[-3] * b0[0x040];
sum -= window[-4] * b1[0x060];
sum -= window[-5] * b0[0x080];
sum -= window[-6] * b1[0x0a0];
sum -= window[-7] * b0[0x0c0];
sum -= window[-8] * b1[0x0e0];
sum -= window[-9] * b0[0x100];
sum -= window[-10] * b1[0x120];
sum -= window[-11] * b0[0x140];
sum -= window[-12] * b1[0x160];
sum -= window[-13] * b0[0x180];
sum -= window[-14] * b1[0x1a0];
sum -= window[-15] * b0[0x1c0];
sum -= window[-16] * b1[0x1e0];
WRITE_SAMPLE(samples,sum,clip);
}
}
return(clip);
}
/*
* -funroll-loops (for gcc) will remove the loops for better performance
* using loops in the source-code enhances readabillity
*/
static void tr(real *here,real *samples)
{
real bufs[64];
{
register int i,j;
register real *b1,*b2,*bs,*costab;
b1 = samples;
bs = bufs;
costab = pnts[0]+16;
b2 = b1 + 32;
for(i=15;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=15;i>=0;i--)
*bs++ = (*--b2 - *b1++) * *--costab;
b1 = bufs;
costab = pnts[1]+8;
b2 = b1 + 16;
{
for(i=7;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=7;i>=0;i--)
*bs++ = (*--b2 - *b1++) * *--costab;
b2 += 32;
costab += 8;
for(i=7;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=7;i>=0;i--)
*bs++ = (*b1++ - *--b2) * *--costab;
b2 += 32;
}
bs = bufs;
costab = pnts[2];
b2 = b1 + 8;
for(j=2;j;j--)
{
for(i=3;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=3;i>=0;i--)
*bs++ = (*--b2 - *b1++) * costab[i];
b2 += 16;
for(i=3;i>=0;i--)
*bs++ = (*b1++ + *--b2);
for(i=3;i>=0;i--)
*bs++ = (*b1++ - *--b2) * costab[i];
b2 += 16;
}
b1 = bufs;
costab = pnts[3];
b2 = b1 + 4;
for(j=4;j;j--)
{
*bs++ = (*b1++ + *--b2);
*bs++ = (*b1++ + *--b2);
*bs++ = (*--b2 - *b1++) * costab[1];
*bs++ = (*--b2 - *b1++) * costab[0];
b2 += 8;
*bs++ = (*b1++ + *--b2);
*bs++ = (*b1++ + *--b2);
*bs++ = (*b1++ - *--b2) * costab[1];
*bs++ = (*b1++ - *--b2) * costab[0];
b2 += 8;
}
bs = bufs;
costab = pnts[4];
b2 = b1 + 2;
for(j=8;j;j--)
{
*bs++ = (*b1++ + *--b2);
*bs++ = (*--b2 - *b1++) * (*costab);
b2 += 4;
*bs++ = (*b1++ + *--b2);
*bs++ = (*b1++ - *--b2) * (*costab);
b2 += 4;
}
}
{
register real *b1;
register int i;
for(b1=bufs,i=8;i;i--,b1+=4)
b1[2] += b1[3];
for(b1=bufs,i=4;i;i--,b1+=8)
{
b1[4] += b1[6];
b1[6] += b1[5];
b1[5] += b1[7];
}
for(b1=bufs,i=2;i;i--,b1+=16)
{
b1[8] += b1[12];
b1[12] += b1[10];
b1[10] += b1[14];
b1[14] += b1[9];
b1[9] += b1[13];
b1[13] += b1[11];
b1[11] += b1[15];
}
#if 0
{
b1 = bufs+16;
b1[0] += b1[8];
b1[8] += b1[4];
b1[4] += b1[12];
b1[12] += b1[2];
b1[2] += b1[10];
b1[10] += b1[6];
b1[6] += b1[14];
b1[14] += b1[1];
b1[1] += b1[9];
b1[9] += b1[5];
b1[5] += b1[13];
b1[13] += b1[3];
b1[3] += b1[11];
b1[11] += b1[7];
b1[7] += b1[15];
}
#endif
}
here[31] = bufs[0]; here[15] = bufs[1]; here[23] = bufs[2]; here[ 7] = bufs[3];
here[27] = bufs[4]; here[11] = bufs[5]; here[19] = bufs[6]; here[ 3] = bufs[7];
here[29] = bufs[8]; here[13] = bufs[9]; here[21] = bufs[10]; here[ 5] = bufs[11];
here[25] = bufs[12]; here[ 9] = bufs[13]; here[17] = bufs[14]; here[ 1] = bufs[15];
#if 0
here[30] = bufs[16]; here[14] = bufs[17]; here[22] = bufs[18]; here[ 6] = bufs[19];
here[26] = bufs[20]; here[10] = bufs[21]; here[18] = bufs[22]; here[ 2] = bufs[23];
here[28] = bufs[24]; here[12] = bufs[25]; here[20] = bufs[26]; here[ 4] = bufs[27];
here[24] = bufs[28]; here[ 8] = bufs[29]; here[16] = bufs[30]; here[ 0] = bufs[31];
#else
here[30] = bufs[16+0]+bufs[16+8]; here[14] = bufs[16+1]+bufs[16+9];
here[22] = bufs[16+2]+bufs[16+10]; here[ 6] = bufs[16+3]+bufs[16+11];
here[26] = bufs[16+4]+bufs[16+12]; here[10] = bufs[16+5]+bufs[16+13];
here[18] = bufs[16+6]+bufs[16+14]; here[ 2] = bufs[16+7]+bufs[16+15];
here[28] = bufs[16+8]+bufs[16+4]; here[12] = bufs[16+9]+bufs[16+5];
here[20] = bufs[16+10]+bufs[16+6]; here[ 4] = bufs[16+11]+bufs[16+7];
here[24] = bufs[16+12]+bufs[16+2]; here[ 8] = bufs[16+13]+bufs[16+3];
here[16] = bufs[16+14]+bufs[16+1]; here[ 0] = bufs[16+15];
#endif
}