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/*
* 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.
* The performance is highly compiler dependend. Maybe
* the decode.c version for 'normal' processor may be faster
* even for Intel processors.
*/
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "mpglib.h"
/* old WRITE_SAMPLE */
#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_mono(struct mpstr *mp,real *bandPtr,unsigned char *samples,int *pnt)
{
short samples_tmp[64];
short *tmp1 = samples_tmp;
int i,ret;
int pnt1 = 0;
ret = synth_1to1(mp,bandPtr,0,(unsigned char *) samples_tmp,&pnt1);
samples += *pnt;
for(i=0;i<32;i++) {
*( (short *) samples) = *tmp1;
samples += 2;
tmp1 += 2;
}
*pnt += 64;
return ret;
}
int synth_1to1(struct mpstr *mp, real *bandPtr,int channel,unsigned char *out,int *pnt)
{
static const int step = 2;
int bo;
short *samples = (short *) (out + *pnt);
real *b0,(*buf)[0x110];
int clip = 0;
int bo1;
bo = mp->synth_bo;
if(!channel) {
bo--;
bo &= 0xf;
buf = mp->synth_buffs[0];
}
else {
samples++;
buf = mp->synth_buffs[1];
}
if(bo & 0x1) {
b0 = buf[0];
bo1 = bo;
dct64(buf[1]+((bo+1)&0xf),buf[0]+bo,bandPtr);
}
else {
b0 = buf[1];
bo1 = bo+1;
dct64(buf[0]+bo,buf[1]+bo+1,bandPtr);
}
mp->synth_bo = bo;
{
register int j;
real *window = decwin + 16 - bo1;
for (j=16;j;j--,b0+=0x10,window+=0x20,samples+=step)
{
real sum;
sum = window[0x0] * b0[0x0];
sum -= window[0x1] * b0[0x1];
sum += window[0x2] * b0[0x2];
sum -= window[0x3] * b0[0x3];
sum += window[0x4] * b0[0x4];
sum -= window[0x5] * b0[0x5];
sum += window[0x6] * b0[0x6];
sum -= window[0x7] * b0[0x7];
sum += window[0x8] * b0[0x8];
sum -= window[0x9] * b0[0x9];
sum += window[0xA] * b0[0xA];
sum -= window[0xB] * b0[0xB];
sum += window[0xC] * b0[0xC];
sum -= window[0xD] * b0[0xD];
sum += window[0xE] * b0[0xE];
sum -= window[0xF] * b0[0xF];
WRITE_SAMPLE(samples,sum,clip);
}
{
real sum;
sum = window[0x0] * b0[0x0];
sum += window[0x2] * b0[0x2];
sum += window[0x4] * b0[0x4];
sum += window[0x6] * b0[0x6];
sum += window[0x8] * b0[0x8];
sum += window[0xA] * b0[0xA];
sum += window[0xC] * b0[0xC];
sum += window[0xE] * b0[0xE];
WRITE_SAMPLE(samples,sum,clip);
b0-=0x10,window-=0x20,samples+=step;
}
window += bo1<<1;
for (j=15;j;j--,b0-=0x10,window-=0x20,samples+=step)
{
real sum;
sum = -window[-0x1] * b0[0x0];
sum -= window[-0x2] * b0[0x1];
sum -= window[-0x3] * b0[0x2];
sum -= window[-0x4] * b0[0x3];
sum -= window[-0x5] * b0[0x4];
sum -= window[-0x6] * b0[0x5];
sum -= window[-0x7] * b0[0x6];
sum -= window[-0x8] * b0[0x7];
sum -= window[-0x9] * b0[0x8];
sum -= window[-0xA] * b0[0x9];
sum -= window[-0xB] * b0[0xA];
sum -= window[-0xC] * b0[0xB];
sum -= window[-0xD] * b0[0xC];
sum -= window[-0xE] * b0[0xD];
sum -= window[-0xF] * b0[0xE];
sum -= window[-0x0] * b0[0xF];
WRITE_SAMPLE(samples,sum,clip);
}
}
*pnt += 128;
return clip;
}
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