--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtwamr/qgain795.c	Mon May 06 04:20:11 2024 +0000
@@ -0,0 +1,580 @@
+/*
+********************************************************************************
+*
+*      GSM AMR-NB speech codec   R98   Version 7.6.0   December 12, 2001
+*                                R99   Version 3.3.0                
+*                                REL-4 Version 4.1.0                
+*
+********************************************************************************
+*
+*      File             : qgain795.c
+*      Purpose          : pitch and codebook gain quantization for MR795
+*
+********************************************************************************
+*/
+
+/*
+********************************************************************************
+*                         MODULE INCLUDE FILE AND VERSION ID
+********************************************************************************
+*/
+#include "namespace.h"
+#include "qgain795.h"
+
+/*
+********************************************************************************
+*                         INCLUDE FILES
+********************************************************************************
+*/
+#include "typedef.h"
+#include "basic_op.h"
+#include "oper_32b.h"
+#include "no_count.h"
+#include "cnst.h"
+#include "log2.h"
+#include "pow2.h"
+#include "sqrt_l.h"
+#include "g_adapt.h"
+#include "calc_en.h"
+#include "q_gain_p.h"
+#include "mac_32.h"
+#include "gains_tab.h"
+
+/*
+********************************************************************************
+*                         LOCAL PROGRAM CODE
+********************************************************************************
+*/
+
+/*************************************************************************
+ *
+ * FUNCTION:  MR795_gain_code_quant3
+ *
+ * PURPOSE: Pre-quantization of codebook gains, given three possible
+ *          LTP gains (using predicted codebook gain)
+ *
+ *************************************************************************/
+static void
+MR795_gain_code_quant3(
+    Word16 exp_gcode0,        /* i  : predicted CB gain (exponent), Q0  */
+    Word16 gcode0,            /* i  : predicted CB gain (norm.),    Q14 */
+    Word16 g_pitch_cand[],    /* i  : Pitch gain candidates (3),    Q14 */
+    Word16 g_pitch_cind[],    /* i  : Pitch gain cand. indices (3), Q0  */
+    Word16 frac_coeff[],      /* i  : coefficients (5),             Q15 */
+    Word16 exp_coeff[],       /* i  : energy coefficients (5),      Q0  */
+                              /*      coefficients from calc_filt_ener()*/
+    Word16 *gain_pit,         /* o  : Pitch gain,                   Q14 */
+    Word16 *gain_pit_ind,     /* o  : Pitch gain index,             Q0  */
+    Word16 *gain_cod,         /* o  : Code gain,                    Q1  */
+    Word16 *gain_cod_ind,     /* o  : Code gain index,              Q0  */
+    Word16 *qua_ener_MR122,   /* o  : quantized energy error,       Q10 */
+                              /*      (for MR122 MA predictor update)   */
+    Word16 *qua_ener          /* o  : quantized energy error,       Q10 */
+                              /*      (for other MA predictor update)   */
+)
+{
+    const Word16 *p;
+    Word16 i, j, cod_ind, pit_ind;
+    Word16 e_max, exp_code;
+    Word16 g_pitch, g2_pitch, g_code, g2_code_h, g2_code_l;
+    Word16 g_pit_cod_h, g_pit_cod_l;
+    Word16 coeff[5], coeff_lo[5];
+    Word16 exp_max[5];
+    Word32 L_tmp, L_tmp0, dist_min;
+
+    /*
+     * The error energy (sum) to be minimized consists of five terms, t[0..4].
+     *
+     *                      t[0] =    gp^2  * <y1 y1>
+     *                      t[1] = -2*gp    * <xn y1>
+     *                      t[2] =    gc^2  * <y2 y2>
+     *                      t[3] = -2*gc    * <xn y2>
+     *                      t[4] =  2*gp*gc * <y1 y2>
+     *
+     */
+
+    /* determine the scaling exponent for g_code: ec = ec0 - 10 */
+    exp_code = sub(exp_gcode0, 10);
+
+    /* calculate exp_max[i] = s[i]-1 */
+    exp_max[0] = sub(exp_coeff[0], 13);                        move16 ();
+    exp_max[1] = sub(exp_coeff[1], 14);                        move16 ();
+    exp_max[2] = add(exp_coeff[2], add(15, shl(exp_code, 1))); move16 ();
+    exp_max[3] = add(exp_coeff[3], exp_code);                  move16 ();
+    exp_max[4] = add(exp_coeff[4], add(exp_code,1));           move16 ();
+
+
+    /*-------------------------------------------------------------------*
+     *  Find maximum exponent:                                           *
+     *  ~~~~~~~~~~~~~~~~~~~~~~                                           *
+     *                                                                   *
+     *  For the sum operation, all terms must have the same scaling;     *
+     *  that scaling should be low enough to prevent overflow. There-    *
+     *  fore, the maximum scale is determined and all coefficients are   *
+     *  re-scaled:                                                       *
+     *                                                                   *
+     *    e_max = max(exp_max[i]) + 1;                                   *
+     *    e = exp_max[i]-e_max;         e <= 0!                          *
+     *    c[i] = c[i]*2^e                                                *
+     *-------------------------------------------------------------------*/
+
+    e_max = exp_max[0];                                        move16 ();
+    for (i = 1; i < 5; i++)     /* implemented flattened */
+    {
+        move16(); test();
+        if (sub(exp_max[i], e_max) > 0)
+        {
+            e_max = exp_max[i];                                move16 ();
+        }
+    }
+
+    e_max = add(e_max, 1);      /* To avoid overflow */
+
+    for (i = 0; i < 5; i++) {
+        j = sub(e_max, exp_max[i]);
+        L_tmp = L_deposit_h(frac_coeff[i]);
+        L_tmp = L_shr(L_tmp, j);
+        L_Extract(L_tmp, &coeff[i], &coeff_lo[i]);
+    }
+
+
+    /*-------------------------------------------------------------------*
+     *  Codebook search:                                                 *
+     *  ~~~~~~~~~~~~~~~~                                                 *
+     *                                                                   *
+     *  For each of the candiates LTP gains in g_pitch_cand[], the terms *
+     *  t[0..4] are calculated from the values in the table (and the     *
+     *  pitch gain candidate) and summed up; the result is the mean      *
+     *  squared error for the LPT/CB gain pair. The index for the mini-  *
+     *  mum MSE is stored and finally used to retrieve the quantized CB  *
+     *  gain                                                             *
+     *-------------------------------------------------------------------*/
+
+    /* start with "infinite" MSE */
+    dist_min = MAX_32;        move16 ();
+    cod_ind = 0;              move16 ();
+    pit_ind = 0;              move16 ();
+
+    /* loop through LTP gain candidates */
+    for (j = 0; j < 3; j++)
+    {
+        /* pre-calculate terms only dependent on pitch gain */
+        g_pitch = g_pitch_cand[j];    move16 ();
+        g2_pitch = mult(g_pitch, g_pitch);
+        L_tmp0 = Mpy_32_16(        coeff[0], coeff_lo[0], g2_pitch);
+        L_tmp0 = Mac_32_16(L_tmp0, coeff[1], coeff_lo[1], g_pitch);
+
+        p = &qua_gain_code[0];
+        for (i = 0; i < NB_QUA_CODE; i++)
+        {
+            g_code = *p++;        move16 (); /* this is g_fac        Q11 */
+            p++;                             /* skip log2(g_fac)         */
+            p++;                             /* skip 20*log10(g_fac)     */
+
+            g_code = mult(g_code, gcode0);
+
+            L_tmp = L_mult (g_code, g_code);
+            L_Extract (L_tmp, &g2_code_h, &g2_code_l);
+
+            L_tmp = L_mult(g_code, g_pitch);
+            L_Extract (L_tmp, &g_pit_cod_h, &g_pit_cod_l);
+
+            L_tmp = Mac_32  (L_tmp0, coeff[2], coeff_lo[2],
+                                     g2_code_h, g2_code_l);
+            L_tmp = Mac_32_16(L_tmp, coeff[3], coeff_lo[3],
+                                     g_code);
+            L_tmp = Mac_32   (L_tmp, coeff[4], coeff_lo[4],
+                                     g_pit_cod_h, g_pit_cod_l);
+
+            /* store table index if MSE for this index is lower
+               than the minimum MSE seen so far; also store the
+               pitch gain for this (so far) lowest MSE          */
+            test ();
+            if (L_sub(L_tmp, dist_min) < (Word32) 0)
+            {
+                dist_min = L_tmp;                move32 ();
+                cod_ind = i;                     move16 ();
+                pit_ind = j;                     move16 ();
+            }
+        }
+    }
+
+    /*------------------------------------------------------------------*
+     *  read quantized gains and new values for MA predictor memories   *
+     *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   *
+     *------------------------------------------------------------------*/
+
+    /* Read the quantized gains */
+    p = &qua_gain_code[add (add (cod_ind, cod_ind), cod_ind)]; move16 ();
+    g_code = *p++;            move16();
+    *qua_ener_MR122 = *p++;   move16();
+    *qua_ener = *p;           move16();
+
+    /*------------------------------------------------------------------*
+     *  calculate final fixed codebook gain:                            *
+     *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                            *
+     *                                                                  *
+     *   gc = gc0 * g                                                   *
+     *------------------------------------------------------------------*/
+
+    L_tmp = L_mult(g_code, gcode0);
+    L_tmp = L_shr(L_tmp, sub(9, exp_gcode0));
+    *gain_cod = extract_h(L_tmp);
+    *gain_cod_ind = cod_ind;                move16 ();
+    *gain_pit = g_pitch_cand[pit_ind];      move16 ();
+    *gain_pit_ind = g_pitch_cind[pit_ind];  move16 ();
+}
+
+
+/*************************************************************************
+ *
+ * FUNCTION:  MR795_gain_code_quant_mod
+ *
+ * PURPOSE: Modified quantization of the MR795 codebook gain
+ *
+ * Uses pre-computed energy coefficients in frac_en[]/exp_en[]
+ *
+ *       frac_en[0]*2^exp_en[0] = <res res>   // LP residual energy
+ *       frac_en[1]*2^exp_en[1] = <exc exc>   // LTP residual energy
+ *       frac_en[2]*2^exp_en[2] = <exc code>  // LTP/CB innovation dot product
+ *       frac_en[3]*2^exp_en[3] = <code code> // CB innovation energy
+ *
+ *************************************************************************/
+static Word16
+MR795_gain_code_quant_mod(  /* o  : index of quantization.            */
+    Word16 gain_pit,        /* i  : pitch gain,                   Q14 */
+    Word16 exp_gcode0,      /* i  : predicted CB gain (exponent), Q0  */
+    Word16 gcode0,          /* i  : predicted CB gain (norm.),    Q14 */
+    Word16 frac_en[],       /* i  : energy coefficients (4),
+                                    fraction part,                Q15 */
+    Word16 exp_en[],        /* i  : energy coefficients (4),
+                                    eponent part,                 Q0  */
+    Word16 alpha,           /* i  : gain adaptor factor (>0),     Q15 */
+    Word16 gain_cod_unq,    /* i  : Code gain (unquantized)           */
+                            /*      (scaling: Q10 - exp_gcode0)       */
+    Word16 *gain_cod,       /* i/o: Code gain (pre-/quantized),   Q1  */
+    Word16 *qua_ener_MR122, /* o  : quantized energy error,       Q10 */
+                            /*      (for MR122 MA predictor update)   */
+    Word16 *qua_ener        /* o  : quantized energy error,       Q10 */
+                            /*      (for other MA predictor update)   */
+ )
+{
+    const Word16 *p;
+    Word16 i, index, tmp;
+    Word16 one_alpha;
+    Word16 exp, e_max;
+    Word16 g2_pitch, g_code;
+    Word16 g2_code_h, g2_code_l;
+    Word16 d2_code_h, d2_code_l;
+    Word16 coeff[5], coeff_lo[5], exp_coeff[5];
+    Word32 L_tmp, L_t0, L_t1, dist_min;
+    Word16 gain_code;
+
+    /*
+      Steps in calculation of the error criterion (dist):
+      ---------------------------------------------------
+
+      underlined = constant; alp = FLP value of alpha, alpha = FIP
+      ----------
+
+
+        ExEn = gp^2 * LtpEn + 2.0*gp*gc[i] * XC + gc[i]^2 * InnEn;
+               ------------   ------         --             -----
+
+        aExEn= alp * ExEn
+             = alp*gp^2*LtpEn + 2.0*alp*gp*XC* gc[i] + alp*InnEn* gc[i]^2
+               --------------   -------------          ---------
+
+             =         t[1]   +              t[2]    +          t[3]
+
+        dist = d1 + d2;
+
+          d1 = (1.0 - alp) * InnEn * (gcu - gc[i])^2 = t[4]
+               -------------------    ---
+
+          d2 =        alp  * (ResEn - 2.0 * sqrt(ResEn*ExEn) + ExEn);
+                      ---     -----   ---        -----
+
+             =        alp  * (sqrt(ExEn) - sqrt(ResEn))^2
+                      ---                  -----------
+
+             =               (sqrt(aExEn) - sqrt(alp*ResEn))^2
+                                            ---------------
+
+             =               (sqrt(aExEn) -       t[0]     )^2
+                                                  ----
+
+     */
+
+    /*
+     * calculate scalings of the constant terms
+     */
+    gain_code = shl (*gain_cod, sub (10, exp_gcode0)); /* Q1  -> Q11 (-ec0) */
+    g2_pitch = mult (gain_pit, gain_pit);              /* Q14 -> Q13        */
+    /* 0 < alpha <= 0.5 => 0.5 <= 1-alpha < 1, i.e one_alpha is normalized  */
+    one_alpha = add (sub (32767, alpha), 1); /* 32768 - alpha */
+
+
+    /*  alpha <= 0.5 -> mult. by 2 to keep precision; compensate in exponent */
+    tmp = extract_h (L_shl (L_mult (alpha, frac_en[1]), 1));
+    /* directly store in 32 bit variable because no further mult. required */
+    L_t1 = L_mult (tmp, g2_pitch);                    move16 ();
+    exp_coeff[1] = sub (exp_en[1], 15);               move16 ();
+
+
+    tmp = extract_h (L_shl (L_mult (alpha, frac_en[2]), 1));
+    coeff[2] = mult (tmp, gain_pit);                  move16 ();
+    exp = sub (exp_gcode0, 10);
+    exp_coeff[2] = add (exp_en[2], exp);              move16 ();
+
+
+    /* alpha <= 0.5 -> mult. by 2 to keep precision; compensate in exponent */
+    coeff[3] = extract_h (L_shl (L_mult (alpha, frac_en[3]), 1));
+    exp = sub (shl (exp_gcode0, 1), 7);
+    exp_coeff[3] = add (exp_en[3], exp);              move16 ();
+
+
+    coeff[4] = mult (one_alpha, frac_en[3]);          move16 ();
+    exp_coeff[4] = add (exp_coeff[3], 1);             move16 ();
+
+
+    L_tmp = L_mult (alpha, frac_en[0]);
+    /* sqrt_l returns normalized value and 2*exponent
+       -> result = val >> (exp/2)
+       exp_coeff holds 2*exponent for c[0]            */
+    /* directly store in 32 bit variable because no further mult. required */
+    L_t0 = sqrt_l_exp (L_tmp, &exp); /* normalization included in sqrt_l_exp */
+                                     move32 (); /* function result */
+    exp = add (exp, 47);
+    exp_coeff[0] = sub (exp_en[0], exp);              move16 ();
+
+    /*
+     * Determine the maximum exponent occuring in the distance calculation
+     * and adjust all fractions accordingly (including a safety margin)
+     *
+     */
+
+    /* find max(e[1..4],e[0]+31) */
+    e_max = add (exp_coeff[0], 31);
+    for (i = 1; i <= 4; i++)
+    {
+        test ();
+        if (sub (exp_coeff[i], e_max) > 0)
+        {
+            e_max = exp_coeff[i];                     move16 ();
+        }
+    }
+
+    /* scale c[1]         (requires no further multiplication) */
+    tmp = sub (e_max, exp_coeff[1]);
+    L_t1 = L_shr(L_t1, tmp);
+
+    /* scale c[2..4] (used in Mpy_32_16 in the quantizer loop) */
+    for (i = 2; i <= 4; i++)
+    {
+        tmp = sub (e_max, exp_coeff[i]);
+        L_tmp = L_deposit_h(coeff[i]);
+        L_tmp = L_shr(L_tmp, tmp);
+        L_Extract(L_tmp, &coeff[i], &coeff_lo[i]);
+    }
+
+    /* scale c[0]         (requires no further multiplication) */
+    exp = sub (e_max, 31);             /* new exponent */
+    tmp = sub (exp, exp_coeff[0]);
+    L_t0 = L_shr (L_t0, shr (tmp, 1));
+    /* perform correction by 1/sqrt(2) if exponent difference is odd */
+    test (); logic16 ();
+    if ((tmp & 0x1) != 0)
+    {
+        L_Extract(L_t0, &coeff[0], &coeff_lo[0]);
+        L_t0 = Mpy_32_16(coeff[0], coeff_lo[0],
+                         23170);                    /* 23170 Q15 = 1/sqrt(2)*/
+    }
+
+    /* search the quantizer table for the lowest value
+       of the search criterion                           */
+    dist_min = MAX_32; move32 ();
+    index = 0;         move16 ();
+    p = &qua_gain_code[0]; move16 ();
+
+    for (i = 0; i < NB_QUA_CODE; i++)
+    {
+        g_code = *p++;        move16 (); /* this is g_fac (Q11)  */
+        p++;                             /* skip log2(g_fac)     */
+        p++;                             /* skip 20*log10(g_fac) */
+        g_code = mult (g_code, gcode0);
+
+        /* only continue if    gc[i]            < 2.0*gc
+           which is equiv. to  g_code (Q10-ec0) < gain_code (Q11-ec0) */
+        test ();
+        if (sub (g_code, gain_code) >= 0)
+            break;
+
+        L_tmp = L_mult (g_code, g_code);
+        L_Extract (L_tmp, &g2_code_h, &g2_code_l);
+
+        tmp = sub (g_code, gain_cod_unq);
+        L_tmp = L_mult (tmp, tmp);
+        L_Extract (L_tmp, &d2_code_h, &d2_code_l);
+
+        /* t2, t3, t4 */
+        L_tmp = Mac_32_16 (L_t1, coeff[2], coeff_lo[2], g_code);
+        L_tmp = Mac_32(L_tmp,    coeff[3], coeff_lo[3], g2_code_h, g2_code_l);
+
+        L_tmp = sqrt_l_exp (L_tmp, &exp);
+        L_tmp = L_shr (L_tmp, shr (exp, 1));
+
+        /* d2 */
+        tmp = round (L_sub (L_tmp, L_t0));
+        L_tmp = L_mult (tmp, tmp);
+
+        /* dist */
+        L_tmp = Mac_32(L_tmp, coeff[4], coeff_lo[4], d2_code_h, d2_code_l);
+
+        /* store table index if distance measure for this
+            index is lower than the minimum seen so far   */
+        test ();
+        if (L_sub (L_tmp, dist_min) < (Word32) 0)
+        {
+            dist_min = L_tmp;                move16 ();
+            index = i;                       move16 ();
+        }
+    }
+
+    /*------------------------------------------------------------------*
+     *  read quantized gains and new values for MA predictor memories   *
+     *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   *
+     *------------------------------------------------------------------*/
+
+    /* Read the quantized gains */
+    p = &qua_gain_code[add (add (index, index), index)]; move16 ();
+    g_code = *p++;            move16();
+    *qua_ener_MR122 = *p++;   move16();
+    *qua_ener = *p;           move16();
+
+    /*------------------------------------------------------------------*
+     *  calculate final fixed codebook gain:                            *
+     *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~                            *
+     *                                                                  *
+     *   gc = gc0 * g                                                   *
+     *------------------------------------------------------------------*/
+
+    L_tmp = L_mult(g_code, gcode0);
+    L_tmp = L_shr(L_tmp, sub(9, exp_gcode0));
+    *gain_cod = extract_h(L_tmp);
+
+    return index;
+}
+
+/*
+********************************************************************************
+*                         PUBLIC PROGRAM CODE
+********************************************************************************
+*/
+
+/*************************************************************************
+ *
+ * FUNCTION:  MR795_gain_quant
+ *
+ * PURPOSE:   pitch and codebook quantization for MR795
+ *
+ *************************************************************************/
+void
+MR795_gain_quant(
+    GainAdaptState *adapt_st, /* i/o: gain adapter state structure       */
+    Word16 res[],             /* i  : LP residual,                  Q0   */
+    Word16 exc[],             /* i  : LTP excitation (unfiltered),  Q0   */
+    Word16 code[],            /* i  : CB innovation (unfiltered),   Q13  */
+    Word16 frac_coeff[],      /* i  : coefficients (5),             Q15  */
+    Word16 exp_coeff[],       /* i  : energy coefficients (5),      Q0   */
+                              /*      coefficients from calc_filt_ener() */
+    Word16 exp_code_en,       /* i  : innovation energy (exponent), Q0   */
+    Word16 frac_code_en,      /* i  : innovation energy (fraction), Q15  */
+    Word16 exp_gcode0,        /* i  : predicted CB gain (exponent), Q0   */
+    Word16 frac_gcode0,       /* i  : predicted CB gain (fraction), Q15  */
+    Word16 L_subfr,           /* i  : Subframe length                    */
+    Word16 cod_gain_frac,     /* i  : opt. codebook gain (fraction),Q15  */
+    Word16 cod_gain_exp,      /* i  : opt. codebook gain (exponent), Q0  */
+    Word16 gp_limit,          /* i  : pitch gain limit                   */
+    Word16 *gain_pit,         /* i/o: Pitch gain,                   Q14  */
+    Word16 *gain_cod,         /* o  : Code gain,                    Q1   */
+    Word16 *qua_ener_MR122,   /* o  : quantized energy error,       Q10  */
+                              /*      (for MR122 MA predictor update)    */
+    Word16 *qua_ener,         /* o  : quantized energy error,       Q10  */
+                              /*      (for other MA predictor update)    */
+    Word16 **anap             /* o  : Index of quantization              */
+                              /*      (first gain pitch, then code pitch)*/
+)
+{
+    Word16 frac_en[4];
+    Word16 exp_en[4];
+    Word16 ltpg, alpha, gcode0;
+    Word16 g_pitch_cand[3];      /* pitch gain candidates   Q14 */
+    Word16 g_pitch_cind[3];      /* pitch gain indices      Q0  */
+    Word16 gain_pit_index;
+    Word16 gain_cod_index;
+    Word16 exp;
+    Word16 gain_cod_unq;         /* code gain (unq.) Q(10-exp_gcode0)  */
+
+
+    /* get list of candidate quantized pitch gain values
+     * and corresponding quantization indices
+     */
+    gain_pit_index = q_gain_pitch (MR795, gp_limit, gain_pit,
+                                   g_pitch_cand, g_pitch_cind); 
+                     move16 (); /* function result */
+
+    /*-------------------------------------------------------------------*
+     *  predicted codebook gain                                          *
+     *  ~~~~~~~~~~~~~~~~~~~~~~~                                          *
+     *  gc0     = 2^exp_gcode0 + 2^frac_gcode0                           *
+     *                                                                   *
+     *  gcode0 (Q14) = 2^14*2^frac_gcode0 = gc0 * 2^(14-exp_gcode0)      *
+     *-------------------------------------------------------------------*/
+    gcode0 = extract_l(Pow2(14, frac_gcode0));          /* Q14 */
+
+    /* pre-quantization of codebook gain
+     * (using three pitch gain candidates);
+     * result: best guess of pitch gain and code gain
+     */
+    MR795_gain_code_quant3(
+        exp_gcode0, gcode0, g_pitch_cand, g_pitch_cind,
+        frac_coeff, exp_coeff,
+        gain_pit, &gain_pit_index, gain_cod, &gain_cod_index,
+        qua_ener_MR122, qua_ener);
+
+    /* calculation of energy coefficients and LTP coding gain */
+    calc_unfilt_energies(res, exc, code, *gain_pit, L_subfr,
+                         frac_en, exp_en, &ltpg);
+
+    /* run gain adaptor, calculate alpha factor to balance LTP/CB gain
+     * (this includes the gain adaptor update)
+     * Note: ltpg = 0 if frac_en[0] == 0, so the update is OK in that case
+     */
+    gain_adapt(adapt_st, ltpg, *gain_cod, &alpha);
+
+    /* if this is a very low energy signal (threshold: see
+     * calc_unfilt_energies) or alpha <= 0 then don't run the modified quantizer
+     */
+    test (); move16 (); test ();
+    if (frac_en[0] != 0 && alpha > 0)
+    {
+        /* innovation energy <cod cod> was already computed in gc_pred() */
+        /* (this overwrites the LtpResEn which is no longer needed)      */
+        frac_en[3] = frac_code_en;          move16 ();
+        exp_en[3] = exp_code_en;            move16 ();
+        
+        /* store optimum codebook gain in Q(10-exp_gcode0) */
+        exp = add (sub (cod_gain_exp, exp_gcode0), 10);
+        gain_cod_unq = shl (cod_gain_frac, exp);
+        
+        /* run quantization with modified criterion */
+        gain_cod_index = MR795_gain_code_quant_mod(
+            *gain_pit, exp_gcode0, gcode0,
+            frac_en, exp_en, alpha, gain_cod_unq,
+            gain_cod, qua_ener_MR122, qua_ener); move16 (); /* function result */
+    }
+
+    *(*anap)++ = gain_pit_index;        move16 ();
+    *(*anap)++ = gain_cod_index;        move16 ();
+}