Initial check in of AMR (NB and WB) decoders based on PV source code.

1 files changed, 1046 insertions, 0 deletions

diff --git a/media/libstagefright/codecs/amrnb/common/src/gc_pred.cpp b/media/libstagefright/codecs/amrnb/common/src/gc_pred.cpp
new file mode 100644
index 0000000..3650f3c
--- /dev/null
+++ b/media/libstagefright/codecs/amrnb/common/src/gc_pred.cpp
@@ -0,0 +1,1046 @@
+/* ------------------------------------------------------------------
+ * Copyright (C) 1998-2009 PacketVideo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ * -------------------------------------------------------------------
+ */
+/****************************************************************************************
+Portions of this file are derived from the following 3GPP standard:
+
+    3GPP TS 26.073
+    ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
+    Available from http://www.3gpp.org
+
+(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
+Permission to distribute, modify and use this file under the standard license
+terms listed above has been obtained from the copyright holder.
+****************************************************************************************/
+/*
+
+ Pathname: ./audio/gsm-amr/c/src/gc_pred.c
+ Functions:
+            gc_pred_reset
+            gc_pred
+            gc_pred_update
+            gc_pred_average_limited
+
+------------------------------------------------------------------------------
+ MODULE DESCRIPTION
+
+ This file contains the functions that perform codebook gain MA prediction.
+
+------------------------------------------------------------------------------
+*/
+
+/*----------------------------------------------------------------------------
+; INCLUDES
+----------------------------------------------------------------------------*/
+#include "gc_pred.h"
+#include "basicop_malloc.h"
+#include "basic_op.h"
+#include "cnst.h"
+#include "log2.h"
+
+/*----------------------------------------------------------------------------
+; MACROS
+; Define module specific macros here
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; DEFINES
+; Include all pre-processor statements here. Include conditional
+; compile variables also.
+----------------------------------------------------------------------------*/
+#define NPRED 4  /* number of prediction taps */
+
+/* average innovation energy.                               */
+/* MEAN_ENER  = 36.0/constant, constant = 20*Log10(2)       */
+#define MEAN_ENER_MR122  783741L  /* 36/(20*log10(2)) (Q17) */
+
+/* minimum quantized energy: -14 dB */
+#define MIN_ENERGY       -14336       /* 14                 Q10 */
+#define MIN_ENERGY_MR122  -2381       /* 14 / (20*log10(2)) Q10 */
+
+/*----------------------------------------------------------------------------
+; LOCAL FUNCTION DEFINITIONS
+; Function Prototype declaration
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; LOCAL VARIABLE DEFINITIONS
+; Variable declaration - defined here and used outside this module
+----------------------------------------------------------------------------*/
+
+/* MA prediction coefficients (Q13) */
+static const Word16 pred[NPRED] = {5571, 4751, 2785, 1556};
+
+/* MA prediction coefficients (Q6)  */
+static const Word16 pred_MR122[NPRED] = {44, 37, 22, 12};
+
+/*
+------------------------------------------------------------------------------
+ FUNCTION NAME: gc_pred_reset
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+    state = pointer to a structure of type gc_predState
+
+ Outputs:
+    past_qua_en field in the structure pointed to by state is initialized
+      to MIN_ENERGY
+    past_qua_en_MR122 field in the structure pointed to by state is
+      initialized to MIN_ENERGY_MR122
+
+ Returns:
+    return_value = 0, if reset was successful; -1, otherwise (int)
+
+ Global Variables Used:
+    None
+
+ Local Variables Needed:
+    None
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function initializes the state memory used by gc_pred to zero.
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+ None
+
+------------------------------------------------------------------------------
+ REFERENCES
+
+ gc_pred.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
+
+------------------------------------------------------------------------------
+ PSEUDO-CODE
+
+int gc_pred_reset (gc_predState *state)
+{
+   Word16 i;
+
+   if (state == (gc_predState *) NULL){
+      fprintf(stderr, "gc_pred_reset: invalid parameter\n");
+      return -1;
+   }
+
+   for(i = 0; i < NPRED; i++)
+   {
+      state->past_qua_en[i] = MIN_ENERGY;
+      state->past_qua_en_MR122[i] = MIN_ENERGY_MR122;
+   }
+  return 0;
+}
+
+------------------------------------------------------------------------------
+ RESOURCES USED [optional]
+
+ When the code is written for a specific target processor the
+ the resources used should be documented below.
+
+ HEAP MEMORY USED: x bytes
+
+ STACK MEMORY USED: x bytes
+
+ CLOCK CYCLES: (cycle count equation for this function) + (variable
+                used to represent cycle count for each subroutine
+                called)
+     where: (cycle count variable) = cycle count for [subroutine
+                                     name]
+
+------------------------------------------------------------------------------
+ CAUTION [optional]
+ [State any special notes, constraints or cautions for users of this function]
+
+------------------------------------------------------------------------------
+*/
+
+Word16 gc_pred_reset(gc_predState *state)
+{
+    Word16 i;
+
+    if (state == (gc_predState *) NULL)
+    {
+        /* fprintf(stderr, "gc_pred_reset: invalid parameter\n"); */
+        return -1;
+    }
+
+    for (i = 0; i < NPRED; i++)
+    {
+        state->past_qua_en[i] = MIN_ENERGY;
+        state->past_qua_en_MR122[i] = MIN_ENERGY_MR122;
+    }
+
+    return(0);
+}
+
+/****************************************************************************/
+
+/*
+------------------------------------------------------------------------------
+ FUNCTION NAME: gc_pred
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+    st = pointer to a structure of type gc_predState
+    mode = AMR mode (enum Mode)
+    code = pointer to the innovative codebook vector; Q12 in MR122 mode,
+           otherwise, Q13 (Word16)
+    exp_gcode0 = pointer to the exponent part of predicted gain factor
+             (Q0) (Word16)
+    frac_gcode0 = pointer to the fractional part of predicted gain factor
+              (Q15) (Word16)
+    exp_en = pointer to the exponent part of the innovation energy; this
+         is calculated for MR795 mode, Q0 (Word16)
+    frac_en = pointer to the fractional part of the innovation energy;
+          this is calculated for MR795 mode, Q15 (Word16)
+    pOverflow = pointer to overflow (Flag)
+
+ Outputs:
+    store pointed to by exp_gcode0 contains the exponent part of the
+      recently calculated predicted gain factor
+    store pointed to by frac_gcode0 contains the fractional part of the
+      recently calculated predicted gain factor
+    store pointed to by exp_en contains the exponent part of the
+      recently calculated innovation energy
+    store pointed to by frac_en contains the fractional part of the
+      recently calculated innovation energy
+    pOverflow = 1 if the math functions called by gc_pred
+                results in overflow else zero.
+
+ Returns:
+    None
+
+ Global Variables Used:
+    None
+
+ Local Variables Needed:
+    pred = table of MA prediction coefficients (Q13) (Word16)
+    pred_MR122 = table of MA prediction coefficients (Q6) (Word16)
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function performs the MA prediction of the innovation energy (in
+ dB/(20*log10(2))), with the mean removed.
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+ None
+
+------------------------------------------------------------------------------
+ REFERENCES
+
+ gc_pred.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
+
+------------------------------------------------------------------------------
+ PSEUDO-CODE
+
+The original etsi reference code uses a global flag Overflow. However, in the
+actual implementation a pointer to a the overflow flag is passed in.
+
+void
+gc_pred(
+    gc_predState *st,   // i/o: State struct
+    enum Mode mode,     // i  : AMR mode
+    Word16 *code,       // i  : innovative codebook vector (L_SUBFR)
+                        //      MR122: Q12, other modes: Q13
+    Word16 *exp_gcode0, // o  : exponent of predicted gain factor, Q0
+    Word16 *frac_gcode0,// o  : fraction of predicted gain factor  Q15
+    Word16 *exp_en,     // o  : exponent of innovation energy,     Q0
+                        //      (only calculated for MR795)
+    Word16 *frac_en     // o  : fraction of innovation energy,     Q15
+                        //      (only calculated for MR795)
+)
+{
+    Word16 i;
+    Word32 ener_code;
+    Word16 exp, frac;
+
+     *-------------------------------------------------------------------*
+     *  energy of code:                                                  *
+     *  ~~~~~~~~~~~~~~~                                                  *
+     *  ener_code = sum(code[i]^2)                                       *
+     *-------------------------------------------------------------------*
+    ener_code = L_mac((Word32) 0, code[0], code[0]);
+                                                 // MR122:  Q12*Q12 -> Q25
+                                                 // others: Q13*Q13 -> Q27
+    for (i = 1; i < L_SUBFR; i++)
+        ener_code = L_mac(ener_code, code[i], code[i]);
+
+    if (sub (mode, MR122) == 0)
+    {
+        Word32 ener;
+
+        // ener_code = ener_code / lcode; lcode = 40; 1/40 = 26214 Q20
+        ener_code = L_mult (pv_round (ener_code), 26214);   // Q9  * Q20 -> Q30
+
+         *-------------------------------------------------------------------*
+         *  energy of code:                                                  *
+         *  ~~~~~~~~~~~~~~~                                                  *
+         *  ener_code(Q17) = 10 * Log10(energy) / constant                   *
+         *                 = 1/2 * Log2(energy)                              *
+         *                                           constant = 20*Log10(2)  *
+         *-------------------------------------------------------------------*
+        // ener_code = 1/2 * Log2(ener_code); Note: Log2=log2+30
+        Log2(ener_code, &exp, &frac);
+        ener_code = L_Comp (sub (exp, 30), frac);     // Q16 for log()
+                                                    // ->Q17 for 1/2 log()
+
+         *-------------------------------------------------------------------*
+         *  predicted energy:                                                *
+         *  ~~~~~~~~~~~~~~~~~                                                *
+         *  ener(Q24) = (Emean + sum{pred[i]*past_en[i]})/constant           *
+         *            = MEAN_ENER + sum(pred[i]*past_qua_en[i])              *
+         *                                           constant = 20*Log10(2)  *
+         *-------------------------------------------------------------------*
+
+        ener = MEAN_ENER_MR122;                      // Q24 (Q17)
+        for (i = 0; i < NPRED; i++)
+        {
+            ener = L_mac (ener, st->past_qua_en_MR122[i], pred_MR122[i]);
+                                                     // Q10 * Q13 -> Q24
+                                                     // Q10 * Q6  -> Q17
+        }
+
+         *-------------------------------------------------------------------*
+         *  predicted codebook gain                                          *
+         *  ~~~~~~~~~~~~~~~~~~~~~~~                                          *
+         *  gc0     = Pow10( (ener*constant - ener_code*constant) / 20 )     *
+         *          = Pow2(ener-ener_code)                                   *
+         *          = Pow2(int(d)+frac(d))                                   *
+         *                                                                   *
+         *  (store exp and frac for pow2())                                  *
+         *-------------------------------------------------------------------*
+
+        ener = L_shr (L_sub (ener, ener_code), 1);                // Q16
+        L_Extract(ener, exp_gcode0, frac_gcode0);
+    }
+    else // all modes except 12.2
+    {
+        Word32 L_tmp;
+        Word16 exp_code, gcode0;
+
+         *-----------------------------------------------------------------*
+         *  Compute: means_ener - 10log10(ener_code/ L_sufr)               *
+         *-----------------------------------------------------------------*
+
+        exp_code = norm_l (ener_code);
+        ener_code = L_shl (ener_code, exp_code);
+
+        // Log2 = log2 + 27
+        Log2_norm (ener_code, exp_code, &exp, &frac);
+
+        // fact = 10/log2(10) = 3.01 = 24660 Q13
+        L_tmp = Mpy_32_16(exp, frac, -24660); // Q0.Q15 * Q13 -> Q14
+
+         *   L_tmp = means_ener - 10log10(ener_code/L_SUBFR)
+         *         = means_ener - 10log10(ener_code) + 10log10(L_SUBFR)
+         *         = K - fact * Log2(ener_code)
+         *         = K - fact * log2(ener_code) - fact*27
+         *
+         *   ==> K = means_ener + fact*27 + 10log10(L_SUBFR)
+         *
+         *   means_ener =       33    =  540672    Q14  (MR475, MR515, MR59)
+         *   means_ener =       28.75 =  471040    Q14  (MR67)
+         *   means_ener =       30    =  491520    Q14  (MR74)
+         *   means_ener =       36    =  589824    Q14  (MR795)
+         *   means_ener =       33    =  540672    Q14  (MR102)
+         *   10log10(L_SUBFR) = 16.02 =  262481.51 Q14
+         *   fact * 27                = 1331640    Q14
+         *   -----------------------------------------
+         *   (MR475, MR515, MR59)   K = 2134793.51 Q14 ~= 16678 * 64 * 2
+         *   (MR67)                 K = 2065161.51 Q14 ~= 32268 * 32 * 2
+         *   (MR74)                 K = 2085641.51 Q14 ~= 32588 * 32 * 2
+         *   (MR795)                K = 2183945.51 Q14 ~= 17062 * 64 * 2
+         *   (MR102)                K = 2134793.51 Q14 ~= 16678 * 64 * 2
+
+
+        if (sub (mode, MR102) == 0)
+        {
+            // mean = 33 dB
+            L_tmp = L_mac(L_tmp, 16678, 64);     // Q14
+        }
+        else if (sub (mode, MR795) == 0)
+        {
+            // ener_code  = <xn xn> * 2^27*2^exp_code
+            // frac_en    = ener_code / 2^16
+            //            = <xn xn> * 2^11*2^exp_code
+            // <xn xn>    = <xn xn>*2^11*2^exp * 2^exp_en
+            //           := frac_en            * 2^exp_en
+
+            // ==> exp_en = -11-exp_code;
+
+            *frac_en = extract_h (ener_code);
+            *exp_en = sub (-11, exp_code);
+
+            // mean = 36 dB
+            L_tmp = L_mac(L_tmp, 17062, 64);     // Q14
+        }
+        else if (sub (mode, MR74) == 0)
+        {
+            // mean = 30 dB
+            L_tmp = L_mac(L_tmp, 32588, 32);     // Q14
+        }
+        else if (sub (mode, MR67) == 0)
+        {
+            // mean = 28.75 dB
+            L_tmp = L_mac(L_tmp, 32268, 32);     // Q14
+        }
+        else // MR59, MR515, MR475
+        {
+            // mean = 33 dB
+            L_tmp = L_mac(L_tmp, 16678, 64);     // Q14
+        }
+
+         *-----------------------------------------------------------------*
+         * Compute gcode0.                                                 *
+         *  = Sum(i=0,3) pred[i]*past_qua_en[i] - ener_code + mean_ener    *
+         *-----------------------------------------------------------------*
+
+        L_tmp = L_shl(L_tmp, 10);                // Q24
+        for (i = 0; i < 4; i++)
+            L_tmp = L_mac(L_tmp, pred[i], st->past_qua_en[i]);
+                                                 // Q13 * Q10 -> Q24
+
+        gcode0 = extract_h(L_tmp);               // Q8
+
+         *-----------------------------------------------------------------*
+         * gcode0 = pow(10.0, gcode0/20)                                   *
+         *        = pow(2, 3.3219*gcode0/20)                               *
+         *        = pow(2, 0.166*gcode0)                                   *
+         *-----------------------------------------------------------------*
+
+        // 5439 Q15 = 0.165985
+        // (correct: 1/(20*log10(2)) 0.166096 = 5443 Q15)
+        if (sub (mode, MR74) == 0) // For IS641 bitexactness
+            L_tmp = L_mult(gcode0, 5439);  // Q8 * Q15 -> Q24
+        else
+            L_tmp = L_mult(gcode0, 5443);  // Q8 * Q15 -> Q24
+
+        L_tmp = L_shr(L_tmp, 8);                   //          -> Q16
+        L_Extract(L_tmp, exp_gcode0, frac_gcode0); //       -> Q0.Q15
+    }
+}
+
+------------------------------------------------------------------------------
+ RESOURCES USED [optional]
+
+ When the code is written for a specific target processor the
+ the resources used should be documented below.
+
+ HEAP MEMORY USED: x bytes
+
+ STACK MEMORY USED: x bytes
+
+ CLOCK CYCLES: (cycle count equation for this function) + (variable
+                used to represent cycle count for each subroutine
+                called)
+     where: (cycle count variable) = cycle count for [subroutine
+                                     name]
+
+------------------------------------------------------------------------------
+ CAUTION [optional]
+ [State any special notes, constraints or cautions for users of this function]
+
+------------------------------------------------------------------------------
+*/
+
+void gc_pred(
+    gc_predState *st,   /* i/o: State struct                           */
+    enum Mode mode,     /* i  : AMR mode                               */
+    Word16 *code,       /* i  : innovative codebook vector (L_SUBFR)   */
+    /*      MR122: Q12, other modes: Q13           */
+    Word16 *exp_gcode0, /* o  : exponent of predicted gain factor, Q0  */
+    Word16 *frac_gcode0,/* o  : fraction of predicted gain factor  Q15 */
+    Word16 *exp_en,     /* o  : exponent of innovation energy,     Q0  */
+    /*      (only calculated for MR795)            */
+    Word16 *frac_en,    /* o  : fraction of innovation energy,     Q15 */
+    /*      (only calculated for MR795)            */
+    Flag   *pOverflow
+)
+{
+    register Word16 i;
+    register Word32 L_temp1, L_temp2;
+    register Word32 L_tmp;
+    Word32 ener_code;
+    Word32 ener;
+    Word16 exp, frac;
+    Word16 exp_code, gcode0;
+    Word16 tmp;
+    Word16 *p_code = &code[0];
+
+    /*-------------------------------------------------------------------*
+     *  energy of code:                                                  *
+     *  ~~~~~~~~~~~~~~~                                                  *
+     *  ener_code = sum(code[i]^2)                                       *
+     *-------------------------------------------------------------------*/
+    ener_code = 0;
+
+    /* MR122:  Q12*Q12 -> Q25 */
+    /* others: Q13*Q13 -> Q27 */
+
+    for (i = L_SUBFR >> 2; i != 0; i--)
+    {
+        tmp = *(p_code++);
+        ener_code += ((Word32) tmp * tmp) >> 3;
+        tmp = *(p_code++);
+        ener_code += ((Word32) tmp * tmp) >> 3;
+        tmp = *(p_code++);
+        ener_code += ((Word32) tmp * tmp) >> 3;
+        tmp = *(p_code++);
+        ener_code += ((Word32) tmp * tmp) >> 3;
+    }
+
+    ener_code <<= 4;
+
+    if (ener_code < 0)      /*  Check for saturation */
+    {
+        ener_code = MAX_32;
+    }
+
+    if (mode == MR122)
+    {
+        /* ener_code = ener_code / lcode; lcode = 40; 1/40 = 26214 Q20 */
+        /* Q9  * Q20 -> Q30 */
+
+        ener_code = ((Word32)(pv_round(ener_code, pOverflow) * 26214)) << 1;
+
+        /*-------------------------------------------------------------*
+         *  energy of code:                                            *
+         *  ~~~~~~~~~~~~~~~                                            *
+         *  ener_code(Q17) = 10 * Log10(energy) / constant             *
+         *                 = 1/2 * Log2(energy)                        *
+         *  constant = 20*Log10(2)                                     *
+         *-------------------------------------------------------------*/
+        /* ener_code = 1/2 * Log2(ener_code); Note: Log2=log2+30 */
+        Log2(ener_code, &exp, &frac, pOverflow);
+
+        /* Q16 for log()    */
+        /* ->Q17 for 1/2 log()*/
+
+        L_temp1 = (Word32)(exp - 30) << 16;
+        ener_code = L_temp1 + ((Word32)frac << 1);
+
+        /*-------------------------------------------------------------*
+         *  predicted energy:                                          *
+         *  ~~~~~~~~~~~~~~~~~                                          *
+         *  ener(Q24) = (Emean + sum{pred[i]*past_en[i]})/constant     *
+         *            = MEAN_ENER + sum(pred[i]*past_qua_en[i])        *
+         *  constant = 20*Log10(2)                                     *
+         *-------------------------------------------------------------*/
+
+        ener = MEAN_ENER_MR122;                   /* Q24 (Q17) */
+        for (i = 0; i < NPRED; i++)
+        {
+            L_temp1 = (((Word32) st->past_qua_en_MR122[i]) *
+                       pred_MR122[i]) << 1;
+            ener = L_add(ener, L_temp1, pOverflow);
+
+            /* Q10 * Q13 -> Q24 */
+            /* Q10 * Q6  -> Q17 */
+        }
+
+        /*---------------------------------------------------------------*
+         *  predicted codebook gain                                      *
+         *  ~~~~~~~~~~~~~~~~~~~~~~~                                      *
+         *  gc0     = Pow10( (ener*constant - ener_code*constant) / 20 ) *
+         *          = Pow2(ener-ener_code)                               *
+         *          = Pow2(int(d)+frac(d))                               *
+         *                                                               *
+         *  (store exp and frac for pow2())                              *
+         *---------------------------------------------------------------*/
+        /* Q16 */
+
+        L_temp1 = L_sub(ener, ener_code, pOverflow);
+
+
+        *exp_gcode0 = (Word16)(L_temp1 >> 17);
+
+        L_temp2 = (Word32) * exp_gcode0 << 15;
+        L_temp1 >>= 2;
+
+        *frac_gcode0 = (Word16)(L_temp1 - L_temp2);
+
+    }
+    else /* all modes except 12.2 */
+    {
+        /*-----------------------------------------------------------------*
+         *  Compute: means_ener - 10log10(ener_code/ L_sufr)               *
+         *-----------------------------------------------------------------*/
+
+        exp_code = norm_l(ener_code);
+        ener_code = L_shl(ener_code, exp_code, pOverflow);
+
+        /* Log2 = log2 + 27 */
+        Log2_norm(ener_code, exp_code, &exp, &frac);
+
+        /* fact = 10/log2(10) = 3.01 = 24660 Q13 */
+        /* Q0.Q15 * Q13 -> Q14 */
+
+        L_temp2 = (((Word32) exp) * -24660) << 1;
+        L_tmp = (((Word32) frac) * -24660) >> 15;
+
+        /* Sign-extend resulting product */
+        if (L_tmp & (Word32) 0x00010000L)
+        {
+            L_tmp = L_tmp | (Word32) 0xffff0000L;
+        }
+
+        L_tmp = L_tmp << 1;
+        L_tmp = L_add(L_tmp, L_temp2, pOverflow);
+
+
+        /*   L_tmp = means_ener - 10log10(ener_code/L_SUBFR)
+         *         = means_ener - 10log10(ener_code) + 10log10(L_SUBFR)
+         *         = K - fact * Log2(ener_code)
+         *         = K - fact * log2(ener_code) - fact*27
+         *
+         *   ==> K = means_ener + fact*27 + 10log10(L_SUBFR)
+         *
+         *   means_ener =       33    =  540672    Q14  (MR475, MR515, MR59)
+         *   means_ener =       28.75 =  471040    Q14  (MR67)
+         *   means_ener =       30    =  491520    Q14  (MR74)
+         *   means_ener =       36    =  589824    Q14  (MR795)
+         *   means_ener =       33    =  540672    Q14  (MR102)
+         *   10log10(L_SUBFR) = 16.02 =  262481.51 Q14
+         *   fact * 27                = 1331640    Q14
+         *   -----------------------------------------
+         *   (MR475, MR515, MR59)   K = 2134793.51 Q14 ~= 16678 * 64 * 2
+         *   (MR67)                 K = 2065161.51 Q14 ~= 32268 * 32 * 2
+         *   (MR74)                 K = 2085641.51 Q14 ~= 32588 * 32 * 2
+         *   (MR795)                K = 2183945.51 Q14 ~= 17062 * 64 * 2
+         *   (MR102)                K = 2134793.51 Q14 ~= 16678 * 64 * 2
+         */
+
+        if (mode == MR102)
+        {
+            /* mean = 33 dB */
+            L_temp2 = (Word32) 16678 << 7;
+            L_tmp = L_add(L_tmp, L_temp2, pOverflow);     /* Q14 */
+        }
+        else if (mode == MR795)
+        {
+            /* ener_code  = <xn xn> * 2^27*2^exp_code
+               frac_en    = ener_code / 2^16
+                          = <xn xn> * 2^11*2^exp_code
+               <xn xn>    = <xn xn>*2^11*2^exp * 2^exp_en
+            :                 = frac_en            * 2^exp_en
+                          ==> exp_en = -11-exp_code;      */
+            *frac_en = (Word16)(ener_code >> 16);
+            *exp_en = sub(-11, exp_code, pOverflow);
+
+            /* mean = 36 dB */
+            L_temp2 = (Word32) 17062 << 7;
+            L_tmp = L_add(L_tmp, L_temp2, pOverflow);     /* Q14 */
+        }
+        else if (mode == MR74)
+        {
+            /* mean = 30 dB */
+            L_temp2 = (Word32) 32588 << 6;
+            L_tmp = L_add(L_tmp, L_temp2, pOverflow);     /* Q14 */
+        }
+        else if (mode == MR67)
+        {
+            /* mean = 28.75 dB */
+            L_temp2 = (Word32) 32268 << 6;
+            L_tmp = L_add(L_tmp, L_temp2, pOverflow);     /* Q14 */
+        }
+        else /* MR59, MR515, MR475 */
+        {
+            /* mean = 33 dB */
+            L_temp2 = (Word32) 16678 << 7;
+            L_tmp = L_add(L_tmp, L_temp2, pOverflow);     /* Q14 */
+        }
+
+        /*-------------------------------------------------------------*
+         * Compute gcode0.                                              *
+         *  = Sum(i=0,3) pred[i]*past_qua_en[i] - ener_code + mean_ener *
+         *--------------------------------------------------------------*/
+        /* Q24 */
+        if (L_tmp > (Word32) 0X001fffffL)
+        {
+            *pOverflow = 1;
+            L_tmp = MAX_32;
+        }
+        else if (L_tmp < (Word32) 0xffe00000L)
+        {
+            *pOverflow = 1;
+            L_tmp = MIN_32;
+        }
+        else
+        {
+            L_tmp = L_tmp << 10;
+        }
+
+        for (i = 0; i < 4; i++)
+        {
+            L_temp2 = ((((Word32) pred[i]) * st->past_qua_en[i]) << 1);
+            L_tmp = L_add(L_tmp, L_temp2, pOverflow);  /* Q13 * Q10 -> Q24 */
+        }
+
+        gcode0 = (Word16)(L_tmp >> 16);               /* Q8  */
+
+        /*-----------------------------------------------------------*
+         * gcode0 = pow(10.0, gcode0/20)                             *
+         *        = pow(2, 3.3219*gcode0/20)                         *
+         *        = pow(2, 0.166*gcode0)                             *
+         *-----------------------------------------------------------*/
+
+        /* 5439 Q15 = 0.165985                                       */
+        /* (correct: 1/(20*log10(2)) 0.166096 = 5443 Q15)            */
+
+        if (mode == MR74) /* For IS641 bitexactness */
+        {
+            L_tmp = (((Word32) gcode0) * 5439) << 1;  /* Q8 * Q15 -> Q24 */
+        }
+        else
+        {
+            L_tmp = (((Word32) gcode0) * 5443) << 1;  /* Q8 * Q15 -> Q24 */
+        }
+
+        if (L_tmp < 0)
+        {
+            L_tmp = ~((~L_tmp) >> 8);
+        }
+        else
+        {
+            L_tmp = L_tmp >> 8;     /* -> Q16 */
+        }
+
+        *exp_gcode0 = (Word16)(L_tmp >> 16);
+        if (L_tmp < 0)
+        {
+            L_temp1 = ~((~L_tmp) >> 1);
+        }
+        else
+        {
+            L_temp1 = L_tmp >> 1;
+        }
+        L_temp2 = (Word32) * exp_gcode0 << 15;
+        *frac_gcode0 = (Word16)(L_sub(L_temp1, L_temp2, pOverflow));
+        /* -> Q0.Q15 */
+    }
+
+    return;
+}
+
+/****************************************************************************/
+
+/*
+------------------------------------------------------------------------------
+ FUNCTION NAME: gc_pred_update
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+    st = pointer to a structure of type gc_predState
+    qua_ener_MR122 = quantized energy for update (Q10); calculated as
+             (log2(qua_err)) (Word16)
+    qua_ener = quantized energy for update (Q10); calculated as
+           (20*log10(qua_err)) (Word16)
+
+ Outputs:
+    structure pointed to by st contains the calculated quantized energy
+      for update
+
+ Returns:
+    None
+
+ Global Variables Used:
+    None
+
+ Local Variables Needed:
+    None
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function updates the MA predictor with the last quantized energy.
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+ None
+
+------------------------------------------------------------------------------
+ REFERENCES
+
+ gc_pred.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
+
+------------------------------------------------------------------------------
+ PSEUDO-CODE
+
+void gc_pred_update(
+    gc_predState *st,      // i/o: State struct
+    Word16 qua_ener_MR122, // i  : quantized energy for update, Q10
+                           //      (log2(qua_err))
+    Word16 qua_ener        // i  : quantized energy for update, Q10
+                           //      (20*log10(qua_err))
+)
+{
+    Word16 i;
+
+    for (i = 3; i > 0; i--)
+    {
+        st->past_qua_en[i] = st->past_qua_en[i - 1];
+        st->past_qua_en_MR122[i] = st->past_qua_en_MR122[i - 1];
+    }
+
+    st->past_qua_en_MR122[0] = qua_ener_MR122;  //    log2 (qua_err), Q10
+
+    st->past_qua_en[0] = qua_ener;              // 20*log10(qua_err), Q10
+
+}
+
+------------------------------------------------------------------------------
+ RESOURCES USED [optional]
+
+ When the code is written for a specific target processor the
+ the resources used should be documented below.
+
+ HEAP MEMORY USED: x bytes
+
+ STACK MEMORY USED: x bytes
+
+ CLOCK CYCLES: (cycle count equation for this function) + (variable
+                used to represent cycle count for each subroutine
+                called)
+     where: (cycle count variable) = cycle count for [subroutine
+                                     name]
+
+------------------------------------------------------------------------------
+ CAUTION [optional]
+ [State any special notes, constraints or cautions for users of this function]
+
+------------------------------------------------------------------------------
+*/
+
+void gc_pred_update(
+    gc_predState *st,      /* i/o: State struct                     */
+    Word16 qua_ener_MR122, /* i  : quantized energy for update, Q10 */
+    /*      (log2(qua_err))                  */
+    Word16 qua_ener        /* i  : quantized energy for update, Q10 */
+    /*      (20*log10(qua_err))              */
+)
+{
+    st->past_qua_en[3] = st->past_qua_en[2];
+    st->past_qua_en_MR122[3] = st->past_qua_en_MR122[2];
+
+    st->past_qua_en[2] = st->past_qua_en[1];
+    st->past_qua_en_MR122[2] = st->past_qua_en_MR122[1];
+
+    st->past_qua_en[1] = st->past_qua_en[0];
+    st->past_qua_en_MR122[1] = st->past_qua_en_MR122[0];
+
+    st->past_qua_en_MR122[0] = qua_ener_MR122; /*    log2 (qua_err), Q10 */
+
+    st->past_qua_en[0] = qua_ener;            /* 20*log10(qua_err), Q10 */
+
+    return;
+}
+
+/****************************************************************************/
+
+/*
+------------------------------------------------------------------------------
+ FUNCTION NAME: gc_pred_average_limited
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+    st = pointer to a structure of type gc_predState
+    ener_avg_MR122 = pointer to the averaged quantized energy (Q10);
+             calculated as (log2(qua_err)) (Word16)
+    ener_avg = pointer to the averaged quantized energy (Q10); calculated
+           as (20*log10(qua_err)) (Word16)
+    pOverflow = pointer to overflow (Flag)
+
+ Outputs:
+    store pointed to by ener_avg_MR122 contains the new averaged quantized
+      energy
+    store pointed to by ener_avg contains the new averaged quantized
+      energy
+    pOverflow = 1 if the math functions called by gc_pred_average_limited
+            results in overflow else zero.
+
+ Returns:
+    None
+
+ Global Variables Used:
+    None
+
+ Local Variables Needed:
+    None
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function calculates the average of MA predictor state values (with a
+ lower limit) used in error concealment.
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+ None
+
+------------------------------------------------------------------------------
+ REFERENCES
+
+ gc_pred.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001
+
+------------------------------------------------------------------------------
+ PSEUDO-CODE
+
+The original etsi reference code uses a global flag Overflow. However, in the
+actual implementation a pointer to a the overflow flag is passed in.
+
+void gc_pred_average_limited(
+    gc_predState *st,       // i: State struct
+    Word16 *ener_avg_MR122, // o: everaged quantized energy,  Q10
+                            //    (log2(qua_err))
+    Word16 *ener_avg        // o: averaged quantized energy,  Q10
+                            //    (20*log10(qua_err))
+)
+{
+    Word16 av_pred_en;
+    Word16 i;
+
+    // do average in MR122 mode (log2() domain)
+    av_pred_en = 0;
+    for (i = 0; i < NPRED; i++)
+    {
+        av_pred_en = add (av_pred_en, st->past_qua_en_MR122[i]);
+    }
+
+    // av_pred_en = 0.25*av_pred_en
+    av_pred_en = mult (av_pred_en, 8192);
+
+    // if (av_pred_en < -14/(20Log10(2))) av_pred_en = ..
+
+    if (sub (av_pred_en, MIN_ENERGY_MR122) < 0)
+    {
+        av_pred_en = MIN_ENERGY_MR122;
+    }
+    *ener_avg_MR122 = av_pred_en;
+
+    // do average for other modes (20*log10() domain)
+    av_pred_en = 0;
+    for (i = 0; i < NPRED; i++)
+    {
+        av_pred_en = add (av_pred_en, st->past_qua_en[i]);
+    }
+
+    // av_pred_en = 0.25*av_pred_en
+    av_pred_en = mult (av_pred_en, 8192);
+
+    // if (av_pred_en < -14) av_pred_en = ..
+
+    if (sub (av_pred_en, MIN_ENERGY) < 0)
+    {
+        av_pred_en = MIN_ENERGY;
+    }
+    *ener_avg = av_pred_en;
+}
+
+------------------------------------------------------------------------------
+ RESOURCES USED [optional]
+
+ When the code is written for a specific target processor the
+ the resources used should be documented below.
+
+ HEAP MEMORY USED: x bytes
+
+ STACK MEMORY USED: x bytes
+
+ CLOCK CYCLES: (cycle count equation for this function) + (variable
+                used to represent cycle count for each subroutine
+                called)
+     where: (cycle count variable) = cycle count for [subroutine
+                                     name]
+
+------------------------------------------------------------------------------
+ CAUTION [optional]
+ [State any special notes, constraints or cautions for users of this function]
+
+------------------------------------------------------------------------------
+*/
+
+void gc_pred_average_limited(
+    gc_predState *st,       /* i: State struct                    */
+    Word16 *ener_avg_MR122, /* o: everaged quantized energy,  Q10 */
+    /*    (log2(qua_err))                 */
+    Word16 *ener_avg,       /* o: averaged quantized energy,  Q10 */
+    /*    (20*log10(qua_err))             */
+    Flag *pOverflow
+)
+{
+    Word16 av_pred_en;
+    register Word16 i;
+
+    /* do average in MR122 mode (log2() domain) */
+    av_pred_en = 0;
+    for (i = 0; i < NPRED; i++)
+    {
+        av_pred_en =
+            add(av_pred_en, st->past_qua_en_MR122[i], pOverflow);
+    }
+
+    /* av_pred_en = 0.25*av_pred_en  (with sign-extension)*/
+    if (av_pred_en < 0)
+    {
+        av_pred_en = (av_pred_en >> 2) | 0xc000;
+    }
+    else
+    {
+        av_pred_en >>= 2;
+    }
+
+    /* if (av_pred_en < -14/(20Log10(2))) av_pred_en = .. */
+    if (av_pred_en < MIN_ENERGY_MR122)
+    {
+        av_pred_en = MIN_ENERGY_MR122;
+    }
+    *ener_avg_MR122 = av_pred_en;
+
+    /* do average for other modes (20*log10() domain) */
+    av_pred_en = 0;
+    for (i = 0; i < NPRED; i++)
+    {
+        av_pred_en = add(av_pred_en, st->past_qua_en[i], pOverflow);
+    }
+
+    /* av_pred_en = 0.25*av_pred_en  (with sign-extension)*/
+    if (av_pred_en < 0)
+    {
+        av_pred_en = (av_pred_en >> 2) | 0xc000;
+    }
+    else
+    {
+        av_pred_en >>= 2;
+    }
+
+    /* if (av_pred_en < -14) av_pred_en = .. */
+    if (av_pred_en < MIN_ENERGY)
+    {
+        av_pred_en = MIN_ENERGY;
+    }
+    *ener_avg = av_pred_en;
+}