/* 
 * 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;
}
