/* l3bitstrea.c */

#include "types.h"
#include "l3mdct.h"
#include "l3loop.h"
#include "layer3.h"
#include "huffman.h"
#include "bitstream.h"
#include "tables.h"
#include "l3bitstream.h" /* the public interface */

static void shine_HuffmanCode(bitstream_t *bs, int table_select, int x, int y);
static void shine_huffman_coder_count1(bitstream_t *bs, const struct huffcodetab *h, int v, int w, int x, int y);

static void encodeSideInfo( shine_global_config *config );
static void encodeMainData( shine_global_config *config );
static void Huffmancodebits( shine_global_config *config, int *ix, gr_info *gi);

/*
  shine_format_bitstream()

  This is called after a frame of audio has been quantized and coded.
  It will write the encoded audio to the bitstream. Note that
  from a layer3 encoder's perspective the bit stream is primarily
  a series of main_data() blocks, with header and side information
  inserted at the proper locations to maintain framing. (See Figure A.7
  in the IS).
*/

void shine_format_bitstream(shine_global_config *config) {
  int gr, ch, i;

  for ( ch =  0; ch < config->wave.channels; ch++ )
    for ( gr = 0; gr < config->mpeg.granules_per_frame; gr++ )
      {
        int *pi = &config->l3_enc[ch][gr][0];
        int *pr = &config->mdct_freq[ch][gr][0];
        for ( i = 0; i < GRANULE_SIZE; i++ )
          {
            if ( (pr[i] < 0) && (pi[i] > 0) )
              pi[i] *= -1;
          }
      }

  encodeSideInfo( config );
  encodeMainData( config );
}

static void encodeMainData(shine_global_config *config) {
  int gr, ch, sfb;
  shine_side_info_t  si = config->side_info;

  for ( gr = 0; gr < config->mpeg.granules_per_frame; gr++ )
    {
      for ( ch = 0; ch < config->wave.channels; ch++ )
        {
          gr_info *gi = &(si.gr[gr].ch[ch].tt);
          unsigned slen1 = shine_slen1_tab[ gi->scalefac_compress ];
          unsigned slen2 = shine_slen2_tab[ gi->scalefac_compress ];
          int *ix = &config->l3_enc[ch][gr][0];

          if ( gr == 0 || si.scfsi[ch][0] == 0 )
            for ( sfb = 0; sfb < 6; sfb++ )
              shine_putbits( &config->bs, config->scalefactor.l[gr][ch][sfb], slen1 );
          if ( gr == 0 || si.scfsi[ch][1] == 0 )
            for ( sfb = 6; sfb < 11; sfb++ )
              shine_putbits( &config->bs, config->scalefactor.l[gr][ch][sfb], slen1 );
          if ( gr == 0 || si.scfsi[ch][2] == 0 )
            for ( sfb = 11; sfb < 16; sfb++ )
              shine_putbits( &config->bs, config->scalefactor.l[gr][ch][sfb], slen2 );
          if ( gr == 0 || si.scfsi[ch][3] == 0 )
            for ( sfb = 16; sfb < 21; sfb++ )
              shine_putbits( &config->bs, config->scalefactor.l[gr][ch][sfb], slen2 );

          Huffmancodebits( config, ix, gi );
        }
    }
}

static void encodeSideInfo( shine_global_config *config ) {
  int gr, ch, scfsi_band, region;
  shine_side_info_t  si = config->side_info;

  shine_putbits( &config->bs, 0x7ff,                             11 );
  shine_putbits( &config->bs, config->mpeg.version,              2 );
  shine_putbits( &config->bs, config->mpeg.layer,                2 );
  shine_putbits( &config->bs, !config->mpeg.crc,                 1 );
  shine_putbits( &config->bs, config->mpeg.bitrate_index,        4 );
  shine_putbits( &config->bs, config->mpeg.samplerate_index % 3, 2 );
  shine_putbits( &config->bs, config->mpeg.padding,              1 );
  shine_putbits( &config->bs, config->mpeg.ext,                  1 );
  shine_putbits( &config->bs, config->mpeg.mode,                 2 );
  shine_putbits( &config->bs, config->mpeg.mode_ext,             2 );
  shine_putbits( &config->bs, config->mpeg.copyright,            1 );
  shine_putbits( &config->bs, config->mpeg.original,             1 );
  shine_putbits( &config->bs, config->mpeg.emph,                 2 );

  if ( config->mpeg.version == MPEG_I ) {
    shine_putbits( &config->bs, 0, 9 );
    if ( config->wave.channels == 2 )
      shine_putbits( &config->bs, si.private_bits, 3 );
    else
      shine_putbits( &config->bs, si.private_bits, 5 );
  } else {
    shine_putbits( &config->bs, 0, 8 );
    if ( config->wave.channels == 2 )
      shine_putbits( &config->bs, si.private_bits, 2 );
    else
      shine_putbits( &config->bs, si.private_bits, 1 );
  }

  if ( config->mpeg.version == MPEG_I )
    for ( ch = 0; ch < config->wave.channels; ch++ ) {
      for ( scfsi_band = 0; scfsi_band < 4; scfsi_band++ )
          shine_putbits( &config->bs, si.scfsi[ch][scfsi_band], 1 );
    }

  for ( gr = 0; gr < config->mpeg.granules_per_frame; gr++ )
    for ( ch = 0; ch < config->wave.channels ; ch++ )
      {
        gr_info *gi = &(si.gr[gr].ch[ch].tt);

        shine_putbits( &config->bs, gi->part2_3_length,        12 );
        shine_putbits( &config->bs, gi->big_values,            9 );
        shine_putbits( &config->bs, gi->global_gain,           8 );
        if ( config->mpeg.version == MPEG_I )
          shine_putbits( &config->bs, gi->scalefac_compress,   4 );
        else
          shine_putbits( &config->bs, gi->scalefac_compress,   9 );
        shine_putbits( &config->bs, 0, 1 );

        for ( region = 0; region < 3; region++ )
          shine_putbits( &config->bs, gi->table_select[region], 5 );

        shine_putbits( &config->bs, gi->region0_count, 4 );
        shine_putbits( &config->bs, gi->region1_count, 3 );

        if ( config->mpeg.version == MPEG_I )
          shine_putbits( &config->bs, gi->preflag,            1 );
        shine_putbits( &config->bs, gi->scalefac_scale,     1 );
        shine_putbits( &config->bs, gi->count1table_select, 1 );
      }
}

/* Note the discussion of huffmancodebits() on pages 28 and 29 of the IS, as
  well as the definitions of the side information on pages 26 and 27. */
static void Huffmancodebits( shine_global_config *config, int *ix, gr_info *gi ) {
  const int *scalefac = &shine_scale_fact_band_index[config->mpeg.samplerate_index][0];
  unsigned scalefac_index;
  int region1Start, region2Start;
  int i, bigvalues, count1End;
  int v, w, x, y;
  const struct huffcodetab *h;
  int bits;

  bits = shine_get_bits_count(&config->bs);

  /* 1: Write the bigvalues */
  bigvalues = gi->big_values << 1;

  scalefac_index = gi->region0_count + 1;
  region1Start = scalefac[ scalefac_index ];
  scalefac_index += gi->region1_count + 1;
  region2Start = scalefac[ scalefac_index ];

  for ( i = 0; i < bigvalues; i += 2 )
    {
      /* get table pointer */
      int idx = (i >= region1Start) + (i >= region2Start);
      unsigned tableindex = gi->table_select[idx];
      /* get huffman code */
      if ( tableindex )
        {
          x = ix[i];
          y = ix[i + 1];
          shine_HuffmanCode( &config->bs, tableindex, x, y );
        }
    }

  /* 2: Write count1 area */
  h = &shine_huffman_table[gi->count1table_select + 32];
  count1End = bigvalues + (gi->count1 <<2);
  for ( i = bigvalues; i < count1End; i += 4 )
    {
      v = ix[i];
      w = ix[i+1];
      x = ix[i+2];
      y = ix[i+3];
      shine_huffman_coder_count1( &config->bs, h, v, w, x, y );
    }

  bits = shine_get_bits_count(&config->bs) - bits;
  bits = gi->part2_3_length - gi->part2_length - bits;
  if (bits)
    {
      int stuffingWords = bits / 32;
      int remainingBits = bits % 32;

      /* Due to the nature of the Huffman code tables, we will pad with ones */
      while ( stuffingWords-- )
        shine_putbits( &config->bs, ~0, 32 );
      if ( remainingBits )
        shine_putbits( &config->bs, (1UL << remainingBits) - 1, remainingBits );
    }
}

static inline int shine_abs_and_sign( int *x ) {
  if ( *x > 0 ) return 0;
  *x *= -1;
  return 1;
}

static void shine_huffman_coder_count1( bitstream_t *bs, const struct huffcodetab *h, int v, int w, int x, int y ) {
  unsigned int signv, signw, signx, signy;
  unsigned int code = 0;
  int p, cbits = 0;

  signv = shine_abs_and_sign( &v );
  signw = shine_abs_and_sign( &w );
  signx = shine_abs_and_sign( &x );
  signy = shine_abs_and_sign( &y );

  p = v + (w << 1) + (x << 2) + (y << 3);
  shine_putbits( bs, h->table[p], h->hlen[p] );

  if ( v ) {
    code = signv;
    cbits = 1;
  }
  if ( w ) {
    code = (code << 1) | signw;
    cbits++;
  }
  if ( x ) {
    code = (code << 1) | signx;
    cbits++;
  }
  if ( y ) {
    code = (code << 1) | signy;
    cbits++;
  }
  shine_putbits( bs, code, cbits );
}

/* Implements the pseudocode of page 98 of the IS */
static void shine_HuffmanCode(bitstream_t *bs, int table_select, int x, int y) {
  int cbits = 0, xbits = 0;
  unsigned int code = 0, ext = 0;
  unsigned signx, signy, ylen, idx;
  const struct huffcodetab *h;

  signx = shine_abs_and_sign( &x );
  signy = shine_abs_and_sign( &y );

  h = &(shine_huffman_table[table_select]);
  ylen = h->ylen;

  if ( table_select > 15 )
    { /* ESC-table is used */
      unsigned linbitsx = 0, linbitsy = 0, linbits = h->linbits;

      if ( x > 14 )
        {
          linbitsx = x - 15;
          x = 15;
        }
      if ( y > 14 )
        {
          linbitsy = y - 15;
          y = 15;
        }

      idx = (x * ylen) + y;
      code  = h->table[idx];
      cbits = h->hlen [idx];
      if ( x > 14 )
        {
          ext   |= linbitsx;
          xbits += linbits;
        }
      if ( x != 0 )
        {
          ext <<= 1;
          ext |= signx;
          xbits += 1;
        }
      if ( y > 14 )
        {
          ext <<= linbits;
          ext |= linbitsy;
          xbits += linbits;
        }
      if ( y != 0 )
        {
          ext <<= 1;
          ext |= signy;
          xbits += 1;
        }

      shine_putbits( bs, code, cbits);
      shine_putbits( bs, ext, xbits);
    }
  else
    { /* No ESC-words */
      idx = (x * ylen) + y;
      code = h->table[idx];
      cbits = h->hlen[idx];
      if ( x != 0 )
        {
          code <<= 1;
          code |= signx;
          cbits += 1;
        }
      if ( y != 0 )
        {
          code <<= 1;
          code |= signy;
          cbits += 1;
        }

      shine_putbits( bs, code, cbits);
    }
}