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short_term.c

/*
 * 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: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/short_term.c,v 1.2 1994/05/10 20:18:47 jutta Exp $ */

#include <stdio.h>
#include <assert.h>

#include "private.h"

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

/*
 *  SHORT TERM ANALYSIS FILTERING SECTION
 */

/* 4.2.8 */

static void Decoding_of_the_coded_Log_Area_Ratios P2((LARc,LARpp),
      word  * LARc,           /* coded log area ratio [0..7]      IN    */
      word  * LARpp)    /* out: decoded ..                  */
{
      register word     temp1 /* , temp2 */;
      register long     ltmp; /* for GSM_ADD */

      /*  This procedure requires for efficient implementation
       *  two tables.
       *
       *  INVA[1..8] = integer( (32768 * 8) / real_A[1..8])
       *  MIC[1..8]  = minimum value of the LARc[1..8]
       */

      /*  Compute the LARpp[1..8]
       */

      /*    for (i = 1; i <= 8; i++, B++, MIC++, INVA++, LARc++, LARpp++) {
       *
       *          temp1  = GSM_ADD( *LARc, *MIC ) << 10;
       *          temp2  = *B << 1;
       *          temp1  = GSM_SUB( temp1, temp2 );
       *
       *          assert(*INVA != MIN_WORD);
       *
       *          temp1  = GSM_MULT_R( *INVA, temp1 );
       *          *LARpp = GSM_ADD( temp1, temp1 );
       *    }
       */

#undef      STEP
#define     STEP( B, MIC, INVA )    \
            temp1    = GSM_ADD( *LARc++, MIC ) << 10; \
            temp1    = GSM_SUB( temp1, B << 1 );            \
            temp1    = GSM_MULT_R( INVA, temp1 );           \
            *LARpp++ = GSM_ADD( temp1, temp1 );

      STEP(      0,  -32,  13107 );
      STEP(      0,  -32,  13107 );
      STEP(   2048,  -16,  13107 );
      STEP(  -2560,  -16,  13107 );

      STEP(     94,   -8,  19223 );
      STEP(  -1792,   -8,  17476 );
      STEP(   -341,   -4,  31454 );
      STEP(  -1144,   -4,  29708 );

      /* NOTE: the addition of *MIC is used to restore
       *     the sign of *LARc.
       */
}

/* 4.2.9 */
/* Computation of the quantized reflection coefficients 
 */

/* 4.2.9.1  Interpolation of the LARpp[1..8] to get the LARp[1..8]
 */

/*
 *  Within each frame of 160 analyzed speech samples the short term
 *  analysis and synthesis filters operate with four different sets of
 *  coefficients, derived from the previous set of decoded LARs(LARpp(j-1))
 *  and the actual set of decoded LARs (LARpp(j))
 *
 * (Initial value: LARpp(j-1)[1..8] = 0.)
 */

static void Coefficients_0_12 P3((LARpp_j_1, LARpp_j, LARp),
      register word * LARpp_j_1,
      register word * LARpp_j,
      register word * LARp)
{
      register int      i;
      register longword ltmp;

      for (i = 1; i <= 8; i++, LARp++, LARpp_j_1++, LARpp_j++) {
            *LARp = GSM_ADD( SASR( *LARpp_j_1, 2 ), SASR( *LARpp_j, 2 ));
            *LARp = GSM_ADD( *LARp,  SASR( *LARpp_j_1, 1));
      }
}

static void Coefficients_13_26 P3((LARpp_j_1, LARpp_j, LARp),
      register word * LARpp_j_1,
      register word * LARpp_j,
      register word * LARp)
{
      register int i;
      register longword ltmp;
      for (i = 1; i <= 8; i++, LARpp_j_1++, LARpp_j++, LARp++) {
            *LARp = GSM_ADD( SASR( *LARpp_j_1, 1), SASR( *LARpp_j, 1 ));
      }
}

static void Coefficients_27_39 P3((LARpp_j_1, LARpp_j, LARp),
      register word * LARpp_j_1,
      register word * LARpp_j,
      register word * LARp)
{
      register int i;
      register longword ltmp;

      for (i = 1; i <= 8; i++, LARpp_j_1++, LARpp_j++, LARp++) {
            *LARp = GSM_ADD( SASR( *LARpp_j_1, 2 ), SASR( *LARpp_j, 2 ));
            *LARp = GSM_ADD( *LARp, SASR( *LARpp_j, 1 ));
      }
}


static void Coefficients_40_159 P2((LARpp_j, LARp),
      register word * LARpp_j,
      register word * LARp)
{
      register int i;

      for (i = 1; i <= 8; i++, LARp++, LARpp_j++)
            *LARp = *LARpp_j;
}

/* 4.2.9.2 */

static void LARp_to_rp P1((LARp),
      register word * LARp)   /* [0..7] IN/OUT  */
/*
 *  The input of this procedure is the interpolated LARp[0..7] array.
 *  The reflection coefficients, rp[i], are used in the analysis
 *  filter and in the synthesis filter.
 */
{
      register int            i;
      register word           temp;
      register longword ltmp;

      for (i = 1; i <= 8; i++, LARp++) {

            /* temp = GSM_ABS( *LARp );
               *
             * if (temp < 11059) temp <<= 1;
             * else if (temp < 20070) temp += 11059;
             * else temp = GSM_ADD( temp >> 2, 26112 );
             *
             * *LARp = *LARp < 0 ? -temp : temp;
             */

            if (*LARp < 0) {
                  temp = *LARp == MIN_WORD ? MAX_WORD : -(*LARp);
                  *LARp = - ((temp < 11059) ? temp << 1
                        : ((temp < 20070) ? temp + 11059
                        :  GSM_ADD( temp >> 2, 26112 )));
            } else {
                  temp  = *LARp;
                  *LARp =    (temp < 11059) ? temp << 1
                        : ((temp < 20070) ? temp + 11059
                        :  GSM_ADD( temp >> 2, 26112 ));
            }
      }
}


/* 4.2.10 */
static void Short_term_analysis_filtering P4((S,rp,k_n,s),
      struct gsm_state * S,
      register word     * rp, /* [0..7]   IN    */
      register int      k_n,  /*   k_end - k_start    */
      register word     * s   /* [0..n-1] IN/OUT      */
)
/*
 *  This procedure computes the short term residual signal d[..] to be fed
 *  to the RPE-LTP loop from the s[..] signal and from the local rp[..]
 *  array (quantized reflection coefficients).  As the call of this
 *  procedure can be done in many ways (see the interpolation of the LAR
 *  coefficient), it is assumed that the computation begins with index
 *  k_start (for arrays d[..] and s[..]) and stops with index k_end
 *  (k_start and k_end are defined in 4.2.9.1).  This procedure also
 *  needs to keep the array u[0..7] in memory for each call.
 */
{
      register word           * u = S->u;
      register int            i;
      register word           di, zzz, ui, sav, rpi;
      register longword       ltmp;

      for (; k_n--; s++) {

            di = sav = *s;

            for (i = 0; i < 8; i++) {           /* YYY */

                  ui    = u[i];
                  rpi   = rp[i];
                  u[i]  = sav;

                  zzz   = GSM_MULT_R(rpi, di);
                  sav   = GSM_ADD(   ui,  zzz);

                  zzz   = GSM_MULT_R(rpi, ui);
                  di    = GSM_ADD(   di,  zzz );
            }

            *s = di;
      }
}

#if defined(USE_FLOAT_MUL) && defined(FAST)

static void Fast_Short_term_analysis_filtering P4((S,rp,k_n,s),
      struct gsm_state * S,
      register word     * rp, /* [0..7]   IN    */
      register int      k_n,  /*   k_end - k_start    */
      register word     * s   /* [0..n-1] IN/OUT      */
)
{
      register word           * u = S->u;
      register int            i;

      float         uf[8],
             rpf[8];

      register float scalef = 3.0517578125e-5;
      register float          sav, di, temp;

      for (i = 0; i < 8; ++i) {
            uf[i]  = u[i];
            rpf[i] = rp[i] * scalef;
      }
      for (; k_n--; s++) {
            sav = di = *s;
            for (i = 0; i < 8; ++i) {
                  register float rpfi = rpf[i];
                  register float ufi  = uf[i];

                  uf[i] = sav;
                  temp  = rpfi * di + ufi;
                  di   += rpfi * ufi;
                  sav   = temp;
            }
            *s = di;
      }
      for (i = 0; i < 8; ++i) u[i] = uf[i];
}
#endif /* ! (defined (USE_FLOAT_MUL) && defined (FAST)) */

static void Short_term_synthesis_filtering P5((S,rrp,k,wt,sr),
      struct gsm_state * S,
      register word     * rrp,      /* [0..7]   IN    */
      register int      k,    /* k_end - k_start      */
      register word     * wt, /* [0..k-1] IN    */
      register word     * sr  /* [0..k-1] OUT   */
)
{
      register word           * v = S->v;
      register int            i;
      register word           sri, tmp1, tmp2;
      register longword ltmp; /* for GSM_ADD  & GSM_SUB */

      while (k--) {
            sri = *wt++;
            for (i = 8; i--;) {

                  /* sri = GSM_SUB( sri, gsm_mult_r( rrp[i], v[i] ) );
                   */
                  tmp1 = rrp[i];
                  tmp2 = v[i];
                  tmp2 =  ( tmp1 == MIN_WORD && tmp2 == MIN_WORD
                        ? MAX_WORD
                        : 0x0FFFF & (( (longword)tmp1 * (longword)tmp2
                                   + 16384) >> 15)) ;

                  sri  = GSM_SUB( sri, tmp2 );

                  /* v[i+1] = GSM_ADD( v[i], gsm_mult_r( rrp[i], sri ) );
                   */
                  tmp1  = ( tmp1 == MIN_WORD && sri == MIN_WORD
                        ? MAX_WORD
                        : 0x0FFFF & (( (longword)tmp1 * (longword)sri
                                   + 16384) >> 15)) ;

                  v[i+1] = GSM_ADD( v[i], tmp1);
            }
            *sr++ = v[0] = sri;
      }
}


#if defined(FAST) && defined(USE_FLOAT_MUL)

static void Fast_Short_term_synthesis_filtering P5((S,rrp,k,wt,sr),
      struct gsm_state * S,
      register word     * rrp,      /* [0..7]   IN    */
      register int      k,    /* k_end - k_start      */
      register word     * wt, /* [0..k-1] IN    */
      register word     * sr  /* [0..k-1] OUT   */
)
{
      register word           * v = S->v;
      register int            i;

      float va[9], rrpa[8];
      register float scalef = 3.0517578125e-5, temp;

      for (i = 0; i < 8; ++i) {
            va[i]   = v[i];
            rrpa[i] = (float)rrp[i] * scalef;
      }
      while (k--) {
            register float sri = *wt++;
            for (i = 8; i--;) {
                  sri -= rrpa[i] * va[i];
                  if     (sri < -32768.) sri = -32768.;
                  else if (sri > 32767.) sri =  32767.;

                  temp = va[i] + rrpa[i] * sri;
                  if     (temp < -32768.) temp = -32768.;
                  else if (temp > 32767.) temp =  32767.;
                  va[i+1] = temp;
            }
            *sr++ = va[0] = sri;
      }
      for (i = 0; i < 9; ++i) v[i] = va[i];
}

#endif /* defined(FAST) && defined(USE_FLOAT_MUL) */

void Gsm_Short_Term_Analysis_Filter P3((S,LARc,s),

      struct gsm_state * S,

      word  * LARc,           /* coded log area ratio [0..7]  IN  */
      word  * s         /* signal [0..159]            IN/OUT      */
)
{
      word        * LARpp_j   = S->LARpp[ S->j      ];
      word        * LARpp_j_1 = S->LARpp[ S->j ^= 1 ];

      word        LARp[8];

#undef      FILTER
#if   defined(FAST) && defined(USE_FLOAT_MUL)
#     define      FILTER      (* (S->fast             \
                     ? Fast_Short_term_analysis_filtering   \
                     : Short_term_analysis_filtering  ))

#else
#     define      FILTER      Short_term_analysis_filtering
#endif

      Decoding_of_the_coded_Log_Area_Ratios( LARc, LARpp_j );

      Coefficients_0_12(  LARpp_j_1, LARpp_j, LARp );
      LARp_to_rp( LARp );
      FILTER( S, LARp, 13, s);

      Coefficients_13_26( LARpp_j_1, LARpp_j, LARp);
      LARp_to_rp( LARp );
      FILTER( S, LARp, 14, s + 13);

      Coefficients_27_39( LARpp_j_1, LARpp_j, LARp);
      LARp_to_rp( LARp );
      FILTER( S, LARp, 13, s + 27);

      Coefficients_40_159( LARpp_j, LARp);
      LARp_to_rp( LARp );
      FILTER( S, LARp, 120, s + 40);
}

void Gsm_Short_Term_Synthesis_Filter P4((S, LARcr, wt, s),
      struct gsm_state * S,

      word  * LARcr,    /* received log area ratios [0..7] IN  */
      word  * wt,       /* received d [0..159]           IN  */

      word  * s         /* signal   s [0..159]          OUT  */
)
{
      word        * LARpp_j   = S->LARpp[ S->j     ];
      word        * LARpp_j_1 = S->LARpp[ S->j ^=1 ];

      word        LARp[8];

#undef      FILTER
#if   defined(FAST) && defined(USE_FLOAT_MUL)

#     define      FILTER      (* (S->fast             \
                     ? Fast_Short_term_synthesis_filtering  \
                     : Short_term_synthesis_filtering ))
#else
#     define      FILTER      Short_term_synthesis_filtering
#endif

      Decoding_of_the_coded_Log_Area_Ratios( LARcr, LARpp_j );

      Coefficients_0_12( LARpp_j_1, LARpp_j, LARp );
      LARp_to_rp( LARp );
      FILTER( S, LARp, 13, wt, s );

      Coefficients_13_26( LARpp_j_1, LARpp_j, LARp);
      LARp_to_rp( LARp );
      FILTER( S, LARp, 14, wt + 13, s + 13 );

      Coefficients_27_39( LARpp_j_1, LARpp_j, LARp);
      LARp_to_rp( LARp );
      FILTER( S, LARp, 13, wt + 27, s + 27 );

      Coefficients_40_159( LARpp_j, LARp );
      LARp_to_rp( LARp );
      FILTER(S, LARp, 120, wt + 40, s + 40);
}

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