/*
  * G.729 decoder
  * 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 <stdlib.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <stdio.h>
 #include <string.h>
 #include <math.h>
 #include <assert.h>
 
 #include "avcodec.h"
 #include "libavutil/avutil.h"

 #include "get_bits.h"

 #include "lsp.h"

 #include "celp_math.h"

 #include "acelp_filters.h"
 #include "acelp_pitch_delay.h"
 #include "acelp_vectors.h"
 #include "g729data.h"
 

 /**

  * minimum quantized LSF value (3.2.4)
  * 0.005 in Q13
  */
 #define LSFQ_MIN                   40
 
 /**
  * maximum quantized LSF value (3.2.4)
  * 3.135 in Q13
  */
 #define LSFQ_MAX                   25681
 
 /**
  * minimum LSF distance (3.2.4)
  * 0.0391 in Q13
  */
 #define LSFQ_DIFF_MIN              321
 
 /**

  * minimum gain pitch value (3.8, Equation 47)
  * 0.2 in (1.14)
  */
 #define SHARP_MIN                  3277
 
 /**
  * maximum gain pitch value (3.8, Equation 47)
  * (EE) This does not comply with the specification.
  * Specification says about 0.8, which should be
  * 13107 in (1.14), but reference C code uses
  * 13017 (equals to 0.7945) instead of it.
  */
 #define SHARP_MAX                  13017
 

 /**
  * subframe size
  */
 #define SUBFRAME_SIZE              40
 
 

 typedef struct {

     uint8_t ac_index_bits[2];   ///< adaptive codebook index for second subframe (size in bits)
     uint8_t parity_bit;         ///< parity bit for pitch delay
     uint8_t gc_1st_index_bits;  ///< gain codebook (first stage) index (size in bits)
     uint8_t gc_2nd_index_bits;  ///< gain codebook (second stage) index (size in bits)
     uint8_t fc_signs_bits;      ///< number of pulses in fixed-codebook vector

     uint8_t fc_indexes_bits;    ///< size (in bits) of fixed-codebook index entry

 } G729FormatDescription;

 typedef struct {

     int pitch_delay_int_prev;   ///< integer part of previous subframe's pitch delay (4.1.3)
 

     /// (2.13) LSP quantizer outputs
     int16_t  past_quantizer_output_buf[MA_NP + 1][10];
     int16_t* past_quantizer_outputs[MA_NP + 1];
 
     int16_t lsfq[10];           ///< (2.13) quantized LSF coefficients from previous frame

     int16_t lsp_buf[2][10];     ///< (0.15) LSP coefficients (previous and current frames) (3.2.5)
     int16_t *lsp[2];            ///< pointers to lsp_buf
 }  G729Context;
 

 static const G729FormatDescription format_g729_8k = {
     .ac_index_bits     = {8,5},
     .parity_bit        = 1,
     .gc_1st_index_bits = GC_1ST_IDX_BITS_8K,
     .gc_2nd_index_bits = GC_2ND_IDX_BITS_8K,
     .fc_signs_bits     = 4,
     .fc_indexes_bits   = 13,
 };
 
 static const G729FormatDescription format_g729d_6k4 = {
     .ac_index_bits     = {8,4},
     .parity_bit        = 0,
     .gc_1st_index_bits = GC_1ST_IDX_BITS_6K4,
     .gc_2nd_index_bits = GC_2ND_IDX_BITS_6K4,
     .fc_signs_bits     = 2,
     .fc_indexes_bits   = 9,
 };
 

 /**

  * \brief pseudo random number generator
  */

 static inline uint16_t g729_prng(uint16_t value)

 {
     return 31821 * value + 13849;
 }
 

 /**
  * Get parity bit of bit 2..7
  */

 static inline int get_parity(uint8_t value)

 {
    return (0x6996966996696996ULL >> (value >> 2)) & 1;
 }
 

 static void lsf_decode(int16_t* lsfq, int16_t* past_quantizer_outputs[MA_NP + 1],
                        int16_t ma_predictor,
                        int16_t vq_1st, int16_t vq_2nd_low, int16_t vq_2nd_high)
 {
     int i,j;
     static const uint8_t min_distance[2]={10, 5}; //(2.13)
     int16_t* quantizer_output = past_quantizer_outputs[MA_NP];
 
     for (i = 0; i < 5; i++) {
         quantizer_output[i]     = cb_lsp_1st[vq_1st][i    ] + cb_lsp_2nd[vq_2nd_low ][i    ];
         quantizer_output[i + 5] = cb_lsp_1st[vq_1st][i + 5] + cb_lsp_2nd[vq_2nd_high][i + 5];
     }
 
     for (j = 0; j < 2; j++) {
         for (i = 1; i < 10; i++) {
             int diff = (quantizer_output[i - 1] - quantizer_output[i] + min_distance[j]) >> 1;
             if (diff > 0) {
                 quantizer_output[i - 1] -= diff;
                 quantizer_output[i    ] += diff;
             }
         }
     }
 
     for (i = 0; i < 10; i++) {
         int sum = quantizer_output[i] * cb_ma_predictor_sum[ma_predictor][i];
         for (j = 0; j < MA_NP; j++)
             sum += past_quantizer_outputs[j][i] * cb_ma_predictor[ma_predictor][j][i];
 
         lsfq[i] = sum >> 15;
     }
 
     /* Rotate past_quantizer_outputs. */
     memmove(past_quantizer_outputs + 1, past_quantizer_outputs, MA_NP * sizeof(int16_t*));
     past_quantizer_outputs[0] = quantizer_output;
 
     ff_acelp_reorder_lsf(lsfq, LSFQ_DIFF_MIN, LSFQ_MIN, LSFQ_MAX, 10);
 }
 

 static av_cold int decoder_init(AVCodecContext * avctx)
 {

     G729Context* ctx = avctx->priv_data;
     int i,k;
 

     if (avctx->channels != 1) {

         av_log(avctx, AV_LOG_ERROR, "Only mono sound is supported (requested channels: %d).\n", avctx->channels);

         return AVERROR(EINVAL);

     }
 

     /* Both 8kbit/s and 6.4kbit/s modes uses two subframes per frame. */
     avctx->frame_size = SUBFRAME_SIZE << 1;
 

     for (k = 0; k < MA_NP + 1; k++) {
         ctx->past_quantizer_outputs[k] = ctx->past_quantizer_output_buf[k];
         for (i = 1; i < 11; i++)
             ctx->past_quantizer_outputs[k][i - 1] = (18717 * i) >> 3;
     }
 

     ctx->lsp[0] = ctx->lsp_buf[0];
     ctx->lsp[1] = ctx->lsp_buf[1];
     memcpy(ctx->lsp[0], lsp_init, 10 * sizeof(int16_t));
 

     return 0;
 }
 

 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
                         AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     int16_t *out_frame = data;
     GetBitContext gb;
     G729FormatDescription format;
     int frame_erasure = 0;    ///< frame erasure detected during decoding
     int bad_pitch = 0;        ///< parity check failed
     int i;

     G729Context *ctx = avctx->priv_data;
     int16_t lp[2][11];           // (3.12)

     uint8_t ma_predictor;     ///< switched MA predictor of LSP quantizer
     uint8_t quantizer_1st;    ///< first stage vector of quantizer
     uint8_t quantizer_2nd_lo; ///< second stage lower vector of quantizer (size in bits)
     uint8_t quantizer_2nd_hi; ///< second stage higher vector of quantizer (size in bits)
 

     int pitch_delay_int;         // pitch delay, integer part
     int pitch_delay_3x;          // pitch delay, multiplied by 3
 

     if (*data_size < SUBFRAME_SIZE << 2) {
         av_log(avctx, AV_LOG_ERROR, "Error processing packet: output buffer too small\n");
         return AVERROR(EIO);
     }
 
     if (buf_size == 10) {
         format = format_g729_8k;
         av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729 @ 8kbit/s");
     } else if (buf_size == 8) {
         format = format_g729d_6k4;
         av_log(avctx, AV_LOG_DEBUG, "Packet type: %s\n", "G.729D @ 6.4kbit/s");
     } else {
         av_log(avctx, AV_LOG_ERROR, "Packet size %d is unknown.\n", buf_size);

         return AVERROR_INVALIDDATA;

     }
 
     for (i=0; i < buf_size; i++)
         frame_erasure |= buf[i];
     frame_erasure = !frame_erasure;
 
     init_get_bits(&gb, buf, buf_size);
 
     ma_predictor     = get_bits(&gb, 1);
     quantizer_1st    = get_bits(&gb, VQ_1ST_BITS);
     quantizer_2nd_lo = get_bits(&gb, VQ_2ND_BITS);
     quantizer_2nd_hi = get_bits(&gb, VQ_2ND_BITS);
 

     lsf_decode(ctx->lsfq, ctx->past_quantizer_outputs,
                ma_predictor,
                quantizer_1st, quantizer_2nd_lo, quantizer_2nd_hi);
 

     ff_acelp_lsf2lsp(ctx->lsp[1], ctx->lsfq, 10);
 
     ff_acelp_lp_decode(&lp[0][0], &lp[1][0], ctx->lsp[1], ctx->lsp[0], 10);
 
     FFSWAP(int16_t*, ctx->lsp[1], ctx->lsp[0]);
 

     for (i = 0; i < 2; i++) {
         uint8_t ac_index;      ///< adaptive codebook index
         uint8_t pulses_signs;  ///< fixed-codebook vector pulse signs
         int fc_indexes;        ///< fixed-codebook indexes
         uint8_t gc_1st_index;  ///< gain codebook (first stage) index
         uint8_t gc_2nd_index;  ///< gain codebook (second stage) index
 
         ac_index      = get_bits(&gb, format.ac_index_bits[i]);
         if(!i && format.parity_bit)
             bad_pitch = get_parity(ac_index) == get_bits1(&gb);
         fc_indexes    = get_bits(&gb, format.fc_indexes_bits);
         pulses_signs  = get_bits(&gb, format.fc_signs_bits);
         gc_1st_index  = get_bits(&gb, format.gc_1st_index_bits);
         gc_2nd_index  = get_bits(&gb, format.gc_2nd_index_bits);
 

         if(!i) {
             if (bad_pitch)
                 pitch_delay_3x   = 3 * ctx->pitch_delay_int_prev;
             else
                 pitch_delay_3x = ff_acelp_decode_8bit_to_1st_delay3(ac_index);
         } else {
             int pitch_delay_min = av_clip(ctx->pitch_delay_int_prev - 5,
                                           PITCH_DELAY_MIN, PITCH_DELAY_MAX - 9);
 
             if(packet_type == FORMAT_G729D_6K4)
                 pitch_delay_3x = ff_acelp_decode_4bit_to_2nd_delay3(ac_index, pitch_delay_min);
             else
                 pitch_delay_3x = ff_acelp_decode_5_6_bit_to_2nd_delay3(ac_index, pitch_delay_min);
         }
 
         /* Round pitch delay to nearest (used everywhere except ff_acelp_interpolate). */
         pitch_delay_int  = (pitch_delay_3x + 1) / 3;
 

         ff_acelp_weighted_vector_sum(fc + pitch_delay_int,
                                      fc + pitch_delay_int,

                                      fc, 1 << 14,
                                      av_clip(ctx->gain_pitch, SHARP_MIN, SHARP_MAX),
                                      0, 14,

                                      SUBFRAME_SIZE - pitch_delay_int);

         if (frame_erasure) {

             ctx->gain_pitch = (29491 * ctx->gain_pitch) >> 15; // 0.90 (0.15)
             ctx->gain_code  = ( 2007 * ctx->gain_code ) >> 11; // 0.98 (0.11)

 
             gain_corr_factor = 0;

         } else {

             ctx->gain_pitch  = cb_gain_1st_8k[gc_1st_index][0] +
                                cb_gain_2nd_8k[gc_2nd_index][0];
             gain_corr_factor = cb_gain_1st_8k[gc_1st_index][1] +
                                cb_gain_2nd_8k[gc_2nd_index][1];

         ff_acelp_weighted_vector_sum(ctx->exc + i * SUBFRAME_SIZE,
                                      ctx->exc + i * SUBFRAME_SIZE, fc,

                                      (!voicing && frame_erasure) ? 0 : ctx->gain_pitch,
                                      ( voicing && frame_erasure) ? 0 : ctx->gain_code,

                                      1 << 13, 14, SUBFRAME_SIZE);

 
             ctx->pitch_delay_int_prev = pitch_delay_int;

     }
 

     *data_size = SUBFRAME_SIZE << 2;
     return buf_size;
 }
 

 AVCodec ff_g729_decoder =

 {
     "g729",

     AVMEDIA_TYPE_AUDIO,

     CODEC_ID_G729,

     sizeof(G729Context),

     decoder_init,

     NULL,
     NULL,

     decode_frame,

     .long_name = NULL_IF_CONFIG_SMALL("G.729"),
 };