/*
  * gain code, gain pitch and pitch delay decoding
  *
  * Copyright (c) 2008 Vladimir Voroshilov
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "avcodec.h"

 #include "dsputil.h"

 #include "acelp_pitch_delay.h"

 #include "celp_math.h"

 
 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
 {
     ac_index += 58;
     if(ac_index > 254)
         ac_index = 3 * ac_index - 510;
     return ac_index;
 }
 
 int ff_acelp_decode_4bit_to_2nd_delay3(
         int ac_index,
         int pitch_delay_min)
 {
     if(ac_index < 4)
         return 3 * (ac_index + pitch_delay_min);
     else if(ac_index < 12)
         return 3 * pitch_delay_min + ac_index + 6;
     else
         return 3 * (ac_index + pitch_delay_min) - 18;
 }
 
 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
         int ac_index,
         int pitch_delay_min)
 {
         return 3 * pitch_delay_min + ac_index - 2;
 }
 
 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
 {
     if(ac_index < 463)
         return ac_index + 105;
     else
         return 6 * (ac_index - 368);
 }
 int ff_acelp_decode_6bit_to_2nd_delay6(
         int ac_index,
         int pitch_delay_min)
 {
     return 6 * pitch_delay_min + ac_index - 3;
 }
 
 void ff_acelp_update_past_gain(
     int16_t* quant_energy,
     int gain_corr_factor,
     int log2_ma_pred_order,
     int erasure)
 {
     int i;
     int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
 
     for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
     {
         avg_gain       += quant_energy[i-1];
         quant_energy[i] = quant_energy[i-1];
     }
 
     if(erasure)
         quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
     else
         quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
 }
 
 int16_t ff_acelp_decode_gain_code(

     DSPContext *dsp,

     int gain_corr_factor,
     const int16_t* fc_v,
     int mr_energy,
     const int16_t* quant_energy,
     const int16_t* ma_prediction_coeff,
     int subframe_size,
     int ma_pred_order)
 {
     int i;
 
     mr_energy <<= 10;
 
     for(i=0; i<ma_pred_order; i++)
         mr_energy += quant_energy[i] * ma_prediction_coeff[i];
 
 #ifdef G729_BITEXACT

     mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);

 
     mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
 
     return bidir_sal(
                ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
                (mr_energy >> 15) - 25
            );
 #else
     mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /

                 sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));

     return mr_energy >> 12;
 #endif
 }