text: /*
   * LucasArts VIMA decoder
   * Copyright (c) 2012 Paul B Mahol
   *
   * 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
   */
  
  /**
   * @file
   * LucasArts VIMA audio decoder
   * @author Paul B Mahol
   */
  
  #include "libavutil/channel_layout.h"
  
  #include "adpcm_data.h"
  #include "avcodec.h"
  #include "get_bits.h"
  #include "internal.h"
  
  static int predict_table_init = 0;
  static uint16_t predict_table[5786 * 2];
  
  static const uint8_t size_table[] = {
      4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
      4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
      4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
      5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
      6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
      7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
  };
  
  static const int8_t index_table1[] = {
      -1, 4, -1, 4
  };
  
  static const int8_t index_table2[] = {
      -1, -1, 2, 6, -1, -1, 2, 6
  };
  
  static const int8_t index_table3[] = {
      -1, -1, -1, -1, 1, 2, 4, 6, -1, -1, -1, -1, 1, 2, 4, 6
  };
  
  static const int8_t index_table4[] = {
      -1, -1, -1, -1, -1, -1, -1, -1, 1,  1,  1,  2,  2,  4,  5,  6,
      -1, -1, -1, -1, -1, -1, -1, -1, 1,  1,  1,  2,  2,  4,  5,  6
  };
  
  static const int8_t index_table5[] = {
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
       1,  1,  1,  1,  1,  2,  2,  2,  2,  4,  4,  4,  5,  5,  6,  6,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
       1,  1,  1,  1,  1,  2,  2,  2,  2,  4,  4,  4,  5,  5,  6,  6
  };
  
  static const int8_t index_table6[] = {
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
       1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,
       2,  2,  4,  4,  4,  4,  4,  4,  5,  5,  5,  5,  6,  6,  6,  6,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
       1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,
       2,  2,  4,  4,  4,  4,  4,  4,  5,  5,  5,  5,  6,  6,  6,  6
  };
  
  static const int8_t *const step_index_tables[] = {
      index_table1, index_table2, index_table3,
      index_table4, index_table5, index_table6
  };
  
  static av_cold int decode_init(AVCodecContext *avctx)
  {
      int start_pos;
  
      avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  
      if (predict_table_init)
          return 0;
  
      for (start_pos = 0; start_pos < 64; start_pos++) {
          unsigned int dest_pos, table_pos;
  
          for (table_pos = 0, dest_pos = start_pos;
               table_pos < FF_ARRAY_ELEMS(ff_adpcm_step_table);
               table_pos++, dest_pos += 64) {
              int put = 0, count, table_value;
  
              table_value = ff_adpcm_step_table[table_pos];
              for (count = 32; count != 0; count >>= 1) {
                  if (start_pos & count)
                      put += table_value;
                  table_value >>= 1;
              }
              predict_table[dest_pos] = put;
          }
      }
      predict_table_init = 1;
  
      return 0;
  }
  
  static int decode_frame(AVCodecContext *avctx, void *data,
                          int *got_frame_ptr, AVPacket *pkt)
  {
      GetBitContext gb;
      AVFrame *frame = data;
      int16_t pcm_data[2];
      uint32_t samples;
      int8_t channel_hint[2];
      int ret, chan;
      int channels = 1;
  
      if (pkt->size < 13)
          return AVERROR_INVALIDDATA;
  
      if ((ret = init_get_bits8(&gb, pkt->data, pkt->size)) < 0)
          return ret;
  
      samples = get_bits_long(&gb, 32);
      if (samples == 0xffffffff) {
          skip_bits_long(&gb, 32);
          samples = get_bits_long(&gb, 32);
      }
  
      if (samples > pkt->size * 2)
          return AVERROR_INVALIDDATA;
  
      channel_hint[0] = get_sbits(&gb, 8);
      if (channel_hint[0] & 0x80) {
          channel_hint[0] = ~channel_hint[0];
          channels = 2;
      }
      avctx->channels = channels;
      avctx->channel_layout = (channels == 2) ? AV_CH_LAYOUT_STEREO
                                              : AV_CH_LAYOUT_MONO;
      pcm_data[0] = get_sbits(&gb, 16);
      if (channels > 1) {
          channel_hint[1] = get_sbits(&gb, 8);
          pcm_data[1]     = get_sbits(&gb, 16);
      }
  
      frame->nb_samples = samples;
      if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
          return ret;
  
      for (chan = 0; chan < channels; chan++) {
          uint16_t *dest = (uint16_t *)frame->data[0] + chan;
          int step_index = channel_hint[chan];
          int output = pcm_data[chan];
          int sample;
  
          for (sample = 0; sample < samples; sample++) {
              int lookup_size, lookup, highbit, lowbits;
  
              step_index  = av_clip(step_index, 0, 88);
              lookup_size = size_table[step_index];
              lookup      = get_bits(&gb, lookup_size);
              highbit     = 1 << (lookup_size - 1);
              lowbits     = highbit - 1;
  
              if (lookup & highbit)
                  lookup ^= highbit;
              else
                  highbit = 0;
  
              if (lookup == lowbits) {
                  output = get_sbits(&gb, 16);
              } else {
                  int predict_index, diff;
  
                  predict_index = (lookup << (7 - lookup_size)) | (step_index << 6);
                  predict_index = av_clip(predict_index, 0, 5785);
                  diff          = predict_table[predict_index];
                  if (lookup)
                      diff += ff_adpcm_step_table[step_index] >> (lookup_size - 1);
                  if (highbit)
                      diff = -diff;
  
                  output = av_clip_int16(output + diff);
              }
  
              *dest = output;
              dest += channels;
  
              step_index += step_index_tables[lookup_size - 2][lookup];
          }
      }
  
      *got_frame_ptr = 1;
  
      return pkt->size;
  }
  
  AVCodec ff_adpcm_vima_decoder = {
      .name         = "adpcm_vima",
      .long_name    = NULL_IF_CONFIG_SMALL("LucasArts VIMA audio"),
      .type         = AVMEDIA_TYPE_AUDIO,
      .id           = AV_CODEC_ID_ADPCM_VIMA,
      .init         = decode_init,
      .decode       = decode_frame,
      .capabilities = AV_CODEC_CAP_DR1,
  };
  
  #if FF_API_VIMA_DECODER
  AVCodec ff_vima_decoder = {
      .name         = "vima",
      .long_name    = NULL_IF_CONFIG_SMALL("LucasArts VIMA audio"),
      .type         = AVMEDIA_TYPE_AUDIO,
      .id           = AV_CODEC_ID_ADPCM_VIMA,
      .init         = decode_init,
      .decode       = decode_frame,
      .capabilities = AV_CODEC_CAP_DR1,
  };
  #endif
  