/*
 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
 * Universitaet Berlin.  See the accompanying file "COPYRIGHT" for
 * details.  THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
 */

/* $Header: /home/kbs/jutta/src/gsm/gsm-1.0/src/RCS/decode.c,v 1.1 1992/10/28 00:15:50 jutta Exp $ */

#include <stdio.h>

#include	"private.h"
#include	"gsm.h"
#include	"proto.h"

/*
 *  4.3 FIXED POINT IMPLEMENTATION OF THE RPE-LTP DECODER
 */

static void Postprocessing P2((S, s),
  struct gsm_state *S, register word * s)
{
  register int k;
  register word msr = S->msr;
  register longword ltmp;       /* for GSM_ADD */
  register word tmp;

  for (k = 160; k--; s++) {
    tmp = GSM_MULT_R(msr, 28180);
    msr = GSM_ADD(*s, tmp);     /* Deemphasis             */
#ifdef USE_ROUNDING_INSTEAD_OF_TRUNCATION
    *s = GSM_ADD(msr, msr);     /* Upscaling by 2 */
    *s = GSM_ADD(*s, 4) & 0xFFF8;       /* Truncation */
#else
    *s = GSM_ADD(msr, msr) & 0xFFF8;    /* Upscaling & Truncation */
#endif
  }
  S->msr = msr;
}

void Gsm_Decoder P8((S, LARcr, Ncr, bcr, Mcr, xmaxcr, xMcr, s), struct gsm_state *S, word * LARcr,      /* [0..7]               IN      */
  word * Ncr,                   /* [0..3]               IN      */
  word * bcr,                   /* [0..3]               IN      */
  word * Mcr,                   /* [0..3]               IN      */
  word * xmaxcr,                /* [0..3]               IN      */
  word * xMcr,                  /* [0..13*4]            IN      */
  word * s)
{                               /* [0..159]               OUT     */
  int j, k;
  word erp[40], wt[160];
  word *drp = S->dp0 + 120;

  for (j = 0; j <= 3; j++, xmaxcr++, bcr++, Ncr++, Mcr++, xMcr += 13) {

    Gsm_RPE_Decoding(S, *xmaxcr, *Mcr, xMcr, erp);
    Gsm_Long_Term_Synthesis_Filtering(S, *Ncr, *bcr, erp, drp);

    for (k = 0; k <= 39; k++)
      wt[j * 40 + k] = drp[k];
  }

  Gsm_Short_Term_Synthesis_Filter(S, LARcr, wt, s);
  Postprocessing(S, s);
}
