/*
  * 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 "libavutil/common.h"

 #include "libavutil/ffmath.h"

 #include "libavutil/float_dsp.h"

 #include "libavutil/mathematics.h"

 #include "avcodec.h"
 #include "acelp_pitch_delay.h"

 #include "celp_math.h"

 #include "audiodsp.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_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;

 }
 
 int16_t ff_acelp_decode_gain_code(

     AudioDSPContext *adsp,

     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(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size));

     return mr_energy >> 12;

 #endif

 }

 
 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
                             float *prediction_error, float energy_mean,
                             const float *pred_table)
 {
     // Equations 66-69:
     // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
     // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
     float val = fixed_gain_factor *

         ff_exp10(0.05 *

               (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +

                energy_mean)) /

         sqrtf(fixed_mean_energy ? fixed_mean_energy : 1.0);

 
     // update quantified prediction error energy history
     memmove(&prediction_error[0], &prediction_error[1],
             3 * sizeof(prediction_error[0]));
     prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
 
     return val;
 }

 
 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
                          const int prev_lag_int, const int subframe,
                          int third_as_first, int resolution)
 {
     /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
     if (subframe == 0 || (subframe == 2 && third_as_first)) {
 
         if (pitch_index < 197)
             pitch_index += 59;
         else
             pitch_index = 3 * pitch_index - 335;
 
     } else {
         if (resolution == 4) {
             int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
                                            PITCH_DELAY_MAX - 9);
 
             // decoding with 4-bit resolution
             if (pitch_index < 4) {
                 // integer only precision for [search_range_min, search_range_min+3]
                 pitch_index = 3 * (pitch_index + search_range_min) + 1;
             } else if (pitch_index < 12) {
                 // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
                 pitch_index += 3 * search_range_min + 7;
             } else {
                 // integer only precision for [search_range_min+6, search_range_min+9]
                 pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
             }
         } else {
             // decoding with 5 or 6 bit resolution, 1/3 fractional precision
             pitch_index--;
 
             if (resolution == 5) {
                 pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
                                            PITCH_DELAY_MAX - 19);
             } else
                 pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
                                            PITCH_DELAY_MAX - 9);
         }
     }
     *lag_int  = pitch_index * 10923 >> 15;
     *lag_frac = pitch_index - 3 * *lag_int - 1;
 }