/*
  * FLAC common code
  * Copyright (c) 2009 Justin Ruggles
  *
  * 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/crc.h"

 #include "flac.h"

 #include "flacdata.h"

 #include "vorbis.h"

 
 static const int8_t sample_size_table[] = { 0, 8, 12, 0, 16, 20, 24, 0 };
 
 static int64_t get_utf8(GetBitContext *gb)
 {
     int64_t val;
     GET_UTF8(val, get_bits(gb, 8), return -1;)
     return val;
 }
 
 int ff_flac_decode_frame_header(AVCodecContext *avctx, GetBitContext *gb,

                                 FLACFrameInfo *fi, int log_level_offset)

 {
     int bs_code, sr_code, bps_code;
 
     /* frame sync code */

     if ((get_bits(gb, 15) & 0x7FFF) != 0x7FFC) {

         av_log(avctx, AV_LOG_ERROR + log_level_offset, "invalid sync code\n");

         return -1;
     }
 
     /* variable block size stream code */

     fi->is_var_size = get_bits1(gb);

 
     /* block size and sample rate codes */
     bs_code = get_bits(gb, 4);
     sr_code = get_bits(gb, 4);
 
     /* channels and decorrelation */
     fi->ch_mode = get_bits(gb, 4);
     if (fi->ch_mode < FLAC_MAX_CHANNELS) {
         fi->channels = fi->ch_mode + 1;

         if (fi->ch_mode <= 5)
             avctx->channel_layout = ff_vorbis_channel_layouts[fi->ch_mode];

         fi->ch_mode = FLAC_CHMODE_INDEPENDENT;
     } else if (fi->ch_mode <= FLAC_CHMODE_MID_SIDE) {
         fi->channels = 2;

         avctx->channel_layout = AV_CH_LAYOUT_STEREO;

     } else {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "invalid channel mode: %d\n", fi->ch_mode);

         return -1;
     }
 
     /* bits per sample */
     bps_code = get_bits(gb, 3);
     if (bps_code == 3 || bps_code == 7) {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "invalid sample size code (%d)\n",

                bps_code);
         return -1;
     }
     fi->bps = sample_size_table[bps_code];
 
     /* reserved bit */
     if (get_bits1(gb)) {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "broken stream, invalid padding\n");

         return -1;
     }
 
     /* sample or frame count */

     fi->frame_or_sample_num = get_utf8(gb);
     if (fi->frame_or_sample_num < 0) {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "sample/frame number invalid; utf8 fscked\n");

         return -1;
     }
 
     /* blocksize */
     if (bs_code == 0) {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "reserved blocksize code: 0\n");

         return -1;
     } else if (bs_code == 6) {
         fi->blocksize = get_bits(gb, 8) + 1;
     } else if (bs_code == 7) {
         fi->blocksize = get_bits(gb, 16) + 1;
     } else {
         fi->blocksize = ff_flac_blocksize_table[bs_code];
     }
 
     /* sample rate */
     if (sr_code < 12) {
         fi->samplerate = ff_flac_sample_rate_table[sr_code];
     } else if (sr_code == 12) {
         fi->samplerate = get_bits(gb, 8) * 1000;
     } else if (sr_code == 13) {
         fi->samplerate = get_bits(gb, 16);
     } else if (sr_code == 14) {
         fi->samplerate = get_bits(gb, 16) * 10;
     } else {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "illegal sample rate code %d\n",

                sr_code);
         return -1;
     }
 
     /* header CRC-8 check */
     skip_bits(gb, 8);
     if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer,
                get_bits_count(gb)/8)) {

         av_log(avctx, AV_LOG_ERROR + log_level_offset,
                "header crc mismatch\n");

         return -1;
     }
 
     return 0;
 }

 
 int ff_flac_get_max_frame_size(int blocksize, int ch, int bps)
 {
     /* Technically, there is no limit to FLAC frame size, but an encoder
        should not write a frame that is larger than if verbatim encoding mode
        were to be used. */
 
     int count;
 
     count = 16;                  /* frame header */
     count += ch * ((7+bps+7)/8); /* subframe headers */
     if (ch == 2) {
         /* for stereo, need to account for using decorrelation */
         count += (( 2*bps+1) * blocksize + 7) / 8;
     } else {
         count += ( ch*bps    * blocksize + 7) / 8;
     }
     count += 2; /* frame footer */
 
     return count;
 }