Function III_huffdecode

modules/data/mp3/libmad/layer3.c:974–1314

NAME: III_huffdecode() DESCRIPTION: decode Huffman code words of one channel of one granule */

   DESCRIPTION:	decode Huffman code words of one channel of one granule
*/
static
enum mad_error III_huffdecode(struct mad_bitptr *ptr, mad_fixed_t xr[576],
                              struct channel *channel,
                              unsigned int const *sfbwidth,
                              unsigned int part2_length)
{
  signed int exponents[39], exp;
  signed int const *expptr;
  struct mad_bitptr peek;
  signed int bits_left, cachesz;
  register mad_fixed_t *xrptr;
  mad_fixed_t const *sfbound;
  register unsigned long bitcache;

  stack(__FUNCTION__, __FILE__, __LINE__);
  bits_left = (signed) channel->part2_3_length - (signed) part2_length;
  if (bits_left < 0)
    return MAD_ERROR_BADPART3LEN;

  III_exponents(channel, sfbwidth, exponents);

  peek = *ptr;
  mad_bit_skip(ptr, bits_left);

  /* align bit reads to byte boundaries */
  cachesz  = mad_bit_bitsleft(&peek);
  cachesz += ((32 - 1 - 24) + (24 - cachesz)) & ~7;

  bitcache   = mad_bit_read(&peek, cachesz);
  bits_left -= cachesz;

  xrptr = &xr[0];

  /* big_values */
  {
    unsigned int region, rcount;
    struct hufftable const *entry;
    union huffpair const *table;
    unsigned int linbits, startbits, big_values, reqhits;
    mad_fixed_t reqcache[16];

    sfbound = xrptr + *sfbwidth++;
    rcount  = channel->region0_count + 1;

    entry     = &mad_huff_pair_table[channel->table_select[region = 0]];
    table     = entry->table;
    linbits   = entry->linbits;
    startbits = entry->startbits;

    if (table == 0)
      return MAD_ERROR_BADHUFFTABLE;

    expptr  = &exponents[0];
    exp     = *expptr++;
    reqhits = 0;

    big_values = channel->big_values;