/*
  * Copyright (c) 2012 Laurent Aimar
  *
  * 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/intreadwrite.h"
 #include "avcodec.h"
 #include "internal.h"

 #include "dvaudio.h"

 
 typedef struct DVAudioContext {
     int block_size;
     int is_12bit;
     int is_pal;
     int16_t shuffle[2000];
 } DVAudioContext;
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     DVAudioContext *s = avctx->priv_data;
     int i;
 

     if (avctx->channels != 2) {

         av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
         return AVERROR(EINVAL);
     }
 
     if (avctx->codec_tag == 0x0215) {
         s->block_size = 7200;
     } else if (avctx->codec_tag == 0x0216) {
         s->block_size = 8640;

     } else if (avctx->block_align == 7200 ||
                avctx->block_align == 8640) {
         s->block_size = avctx->block_align;

     } else {
         return AVERROR(EINVAL);
     }
 

     s->is_pal = s->block_size == 8640;

     s->is_12bit = avctx->bits_per_coded_sample == 12;

     avctx->sample_fmt = AV_SAMPLE_FMT_S16;

     avctx->channel_layout = AV_CH_LAYOUT_STEREO;

 
     for (i = 0; i < FF_ARRAY_ELEMS(s->shuffle); i++) {
         const unsigned a = s->is_pal ? 18 : 15;
         const unsigned b = 3 * a;
 
         s->shuffle[i] = 80 * ((21 * (i % 3) + 9 * (i / 3) + ((i / a) % 3)) % b) +
                          (2 + s->is_12bit) * (i / b) + 8;
     }
 
     return 0;
 }
 
 static inline uint16_t dv_audio_12to16(uint16_t sample)
 {
     uint16_t shift, result;
 
     sample = (sample < 0x800) ? sample : sample | 0xf000;
     shift  = (sample & 0xf00) >> 8;
 
     if (shift < 0x2 || shift > 0xd) {
         result = sample;
     } else if (shift < 0x8) {
         shift--;
         result = (sample - (256 * shift)) << shift;
     } else {
         shift  = 0xe - shift;
         result = ((sample + ((256 * shift) + 1)) << shift) - 1;
     }
 
     return result;
 }
 
 static int decode_frame(AVCodecContext *avctx, void *data,
                         int *got_frame_ptr, AVPacket *pkt)
 {
     DVAudioContext *s = avctx->priv_data;
     AVFrame *frame = data;
     const uint8_t *src = pkt->data;
     int16_t *dst;
     int ret, i;
 

     if (pkt->size < s->block_size)

         return AVERROR_INVALIDDATA;
 
     frame->nb_samples = dv_get_audio_sample_count(pkt->data + 244, s->is_pal);
     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
         return ret;
     dst = (int16_t *)frame->data[0];
 
     for (i = 0; i < frame->nb_samples; i++) {
        const uint8_t *v = &src[s->shuffle[i]];
 
        if (s->is_12bit) {
            *dst++ = dv_audio_12to16((v[0] << 4) | ((v[2] >> 4) & 0x0f));
            *dst++ = dv_audio_12to16((v[1] << 4) | ((v[2] >> 0) & 0x0f));
        } else {
            *dst++ = AV_RB16(&v[0]);
            *dst++ = AV_RB16(&v[s->is_pal ? 4320 : 3600]);
        }
     }
 
     *got_frame_ptr = 1;
 

     return s->block_size;

 }
 
 AVCodec ff_dvaudio_decoder = {
     .name           = "dvaudio",
     .long_name      = NULL_IF_CONFIG_SMALL("Ulead DV Audio"),
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = AV_CODEC_ID_DVAUDIO,
     .init           = decode_init,
     .decode         = decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
     .priv_data_size = sizeof(DVAudioContext),
 };