/*
  * Westwood SNDx codecs
  * Copyright (c) 2005 Konstantin Shishkov
  *

  * 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 <stdint.h>

 #include "libavutil/channel_layout.h"

 #include "libavutil/common.h"

 #include "libavutil/intreadwrite.h"

 #include "avcodec.h"

 #include "internal.h"

 
 /**

  * @file

  * Westwood SNDx codecs

  *
  * Reference documents about VQA format and its audio codecs
  * can be found here:
  * http://www.multimedia.cx
  */
 

 static const int8_t ws_adpcm_4bit[] = {

     -9, -8, -6, -5, -4, -3, -2, -1,

      0,  1,  2,  3,  4,  5,  6,  8
 };

 static av_cold int ws_snd_decode_init(AVCodecContext *avctx)

 {

     avctx->channels       = 1;
     avctx->channel_layout = AV_CH_LAYOUT_MONO;
     avctx->sample_fmt     = AV_SAMPLE_FMT_U8;

     return 0;
 }
 

 static int ws_snd_decode_frame(AVCodecContext *avctx, void *data,

                                int *got_frame_ptr, AVPacket *avpkt)

 {

     AVFrame *frame     = data;

     const uint8_t *buf = avpkt->data;

     int buf_size       = avpkt->size;

     int in_size, out_size, ret;

     int sample = 128;

     uint8_t *samples;

     uint8_t *samples_end;

     if (!buf_size)
         return 0;
 

     if (buf_size < 4) {
         av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
         return AVERROR(EINVAL);
     }
 

     out_size = AV_RL16(&buf[0]);

     in_size  = AV_RL16(&buf[2]);

     buf += 4;

     if (in_size > buf_size) {
         av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");

         return AVERROR_INVALIDDATA;

     }

 
     /* get output buffer */

     frame->nb_samples = out_size;
     if ((ret = ff_get_buffer(avctx, frame)) < 0) {

         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;
     }

     samples     = frame->data[0];

     samples_end = samples + out_size;

     if (in_size == out_size) {

         memcpy(samples, buf, out_size);

         *got_frame_ptr = 1;

         return buf_size;
     }

     while (samples < samples_end && buf - avpkt->data < buf_size) {

         int code, smp, size;

         uint8_t count;

         code  = *buf >> 6;
         count = *buf & 0x3F;

         buf++;

         /* make sure we don't write past the output buffer */

         switch (code) {

         case 0:  smp = 4 * (count + 1);                break;
         case 1:  smp = 2 * (count + 1);                break;

         case 2:  smp = (count & 0x20) ? 1 : count + 1; break;
         default: smp = count + 1;                      break;
         }

         if (samples_end - samples < smp)

             break;
 
         /* make sure we don't read past the input buffer */
         size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1;
         if ((buf - avpkt->data) + size > buf_size)
             break;
 

         switch (code) {

         case 0: /* ADPCM 2-bit */
             for (count++; count > 0; count--) {
                 code = *buf++;

                 sample += ( code       & 0x3) - 2;

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

                 sample += ((code >> 2) & 0x3) - 2;

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

                 sample += ((code >> 4) & 0x3) - 2;

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

                 sample +=  (code >> 6)        - 2;

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

             }
             break;
         case 1: /* ADPCM 4-bit */
             for (count++; count > 0; count--) {
                 code = *buf++;
                 sample += ws_adpcm_4bit[code & 0xF];

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

                 sample += ws_adpcm_4bit[code >> 4];

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

             }
             break;
         case 2: /* no compression */
             if (count & 0x20) { /* big delta */

                 int8_t t;

                 t = count;
                 t <<= 3;
                 sample += t >> 3;

                 sample = av_clip_uint8(sample);
                 *samples++ = sample;

             } else { /* copy */

                 memcpy(samples, buf, smp);
                 samples += smp;
                 buf     += smp;

                 sample = buf[-1];

             }
             break;
         default: /* run */

             memset(samples, sample, smp);
             samples += smp;

         }
     }

     frame->nb_samples = samples - frame->data[0];
     *got_frame_ptr    = 1;

     return buf_size;
 }
 

 AVCodec ff_ws_snd1_decoder = {

     .name           = "ws_snd1",
     .type           = AVMEDIA_TYPE_AUDIO,

     .id             = AV_CODEC_ID_WESTWOOD_SND1,

     .init           = ws_snd_decode_init,
     .decode         = ws_snd_decode_frame,

     .capabilities   = CODEC_CAP_DR1,

     .long_name      = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),

 };