/* 
 * 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 "mpg123.h"
#include "mpglib.h"

extern struct mpstr *gmp;

 /* 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 (real * bandPtr, unsigned char *samples, int *pnt)
{
  short samples_tmp[64];
  short *tmp1 = samples_tmp;
  int i, ret;
  int pnt1 = 0;

  ret = synth_1to1 (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 (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 = gmp->synth_bo;

  if (!channel)
    {
      bo--;
      bo &= 0xf;
      buf = gmp->synth_buffs[0];
    }
  else
    {
      samples++;
      buf = gmp->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);
    }

  gmp->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;
}
