/*

  * 8SVX audio decoder

  * Copyright (C) 2008 Jaikrishnan Menon
  *
  * 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 libavcodec/8svx.c

  * 8svx audio decoder
  * @author Jaikrishnan Menon
  * supports: fibonacci delta encoding
  *         : exponential encoding
  */
 
 #include "avcodec.h"
 

 /** decoder context */

 typedef struct EightSvxContext {
     int16_t fib_acc;

     const int16_t *table;

 } EightSvxContext;
 

 static const int16_t fibonacci[16]   = { -34<<8, -21<<8, -13<<8,  -8<<8, -5<<8, -3<<8, -2<<8, -1<<8,

                                           0, 1<<8, 2<<8, 3<<8, 5<<8, 8<<8, 13<<8, 21<<8 };

 static const int16_t exponential[16] = { -128<<8, -64<<8, -32<<8, -16<<8, -8<<8, -4<<8, -2<<8, -1<<8,

                                           0, 1<<8, 2<<8, 4<<8, 8<<8, 16<<8, 32<<8, 64<<8 };
 

 /** decode a frame */

 static int eightsvx_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
                                  const uint8_t *buf, int buf_size)
 {
     EightSvxContext *esc = avctx->priv_data;
     int16_t *out_data = data;
     int consumed = buf_size;
     const uint8_t *buf_end = buf + buf_size;
 
     if((*data_size >> 2) < buf_size)
         return -1;
 
     if(avctx->frame_number == 0) {
         esc->fib_acc = buf[1] << 8;
         buf_size -= 2;
         buf += 2;
     }
 
     *data_size = buf_size << 2;
 
     while(buf < buf_end) {
         uint8_t d = *buf++;
         esc->fib_acc += esc->table[d & 0x0f];
         *out_data++ = esc->fib_acc;
         esc->fib_acc += esc->table[d >> 4];
         *out_data++ = esc->fib_acc;
     }
 
     return consumed;
 }
 

 /** initialize 8svx decoder */

 static av_cold int eightsvx_decode_init(AVCodecContext *avctx)
 {
     EightSvxContext *esc = avctx->priv_data;
 
     switch(avctx->codec->id) {
         case CODEC_ID_8SVX_FIB:
           esc->table = fibonacci;
           break;
         case CODEC_ID_8SVX_EXP:
           esc->table = exponential;
           break;
         default:
           return -1;
     }

     avctx->sample_fmt = SAMPLE_FMT_S16;

     return 0;
 }
 
 AVCodec eightsvx_fib_decoder = {

   .name           = "8svx_fib",

   .type           = CODEC_TYPE_AUDIO,
   .id             = CODEC_ID_8SVX_FIB,
   .priv_data_size = sizeof (EightSvxContext),
   .init           = eightsvx_decode_init,
   .decode         = eightsvx_decode_frame,

   .long_name      = NULL_IF_CONFIG_SMALL("8SVX fibonacci"),

 };
 
 AVCodec eightsvx_exp_decoder = {

   .name           = "8svx_exp",

   .type           = CODEC_TYPE_AUDIO,
   .id             = CODEC_ID_8SVX_EXP,
   .priv_data_size = sizeof (EightSvxContext),
   .init           = eightsvx_decode_init,
   .decode         = eightsvx_decode_frame,

   .long_name      = NULL_IF_CONFIG_SMALL("8SVX exponential"),

 };