huffman.c

mp3 source code decoder & encoder

{ 4, 4, 0,   0,t6HB, t6l},
{ 6, 6, 0,   0,t7HB, t7l},
{ 6, 6, 0,   0,t8HB, t8l},
{ 6, 6, 0,   0,t9HB, t9l},
{ 8, 8, 0,   0,t10HB, t10l},
{ 8, 8, 0,   0,t11HB, t11l},
{ 8, 8, 0,   0,t12HB, t12l},
{16,16, 0,   0,t13HB, t13l},
{ 0, 0, 0,   0,NULL,NULL},/* Apparently not used */
{16,16, 0,   0,t15HB, t15l},
{16,16, 1,   1,t16HB, t16l},
{16,16, 2,   3,t16HB, t16l},
{16,16, 3,   7,t16HB, t16l},
{16,16, 4,  15,t16HB, t16l},
{16,16, 6,  63,t16HB, t16l},
{16,16, 8, 255,t16HB, t16l},
{16,16,10,1023,t16HB, t16l},
{16,16,13,8191,t16HB, t16l},
{16,16, 4,  15,t24HB, t24l},
{16,16, 5,  31,t24HB, t24l},
{16,16, 6,  63,t24HB, t24l},
{16,16, 7, 127,t24HB, t24l},
{16,16, 8, 255,t24HB, t24l},
{16,16, 9, 511,t24HB, t24l},
{16,16,11,2047,t24HB, t24l},
{16,16,13,8191,t24HB, t24l},
{ 1,16, 0,   0,t32HB, t32l},
{ 1,16, 0,   0,t33HB, t33l},
};	

/* do the huffman coding,  */
/* note! for counta,countb - the 4 bit value is passed in y, set x to 0 */
/* return value: 0-no error, 1 decode error				*/
void huffman_coder(unsigned int x,
                   unsigned int y,
                   struct huffcodetab *h,
                   L3_bitstream_t *bs)
{
  HUFFBITS huffbits; /* data left aligned */
  HUFFBITS linbitsX; 
  HUFFBITS linbitsY;
  unsigned int len;
  unsigned int xl1 = h->xlen-1;
  unsigned int yl1 = h->ylen-1;
  linbitsX = 0;
  linbitsY = 0;
  if (h->table == NULL) return;
  if (((x < xl1) || (xl1==0)) && (y < yl1)) {
    huffbits = h->table[x*(h->xlen)+y];
    len = h->hlen[x*(h->xlen)+y];
    putbits(bs,huffbits,len);
    return;
  }  
  else if (x >= xl1) {
    linbitsX = x-xl1;
    if (linbitsX > h->linmax) {
      linbitsX= h->linmax;
    };
    if (y >= yl1) {
      huffbits = h->table[(h->ylen)*(h->xlen)-1];
      len = h->hlen[(h->ylen)*(h->xlen)-1];
      putbits(bs,huffbits,len);
      linbitsY = y-yl1;
      if (linbitsY > h->linmax) {
        linbitsY = h->linmax;
      };
      if (h->linbits) {
        putbits(bs,linbitsX,h->linbits);
        putbits(bs,linbitsY,h->linbits);
      }
    } 
    else { /* x>= h->xlen, y<h->ylen */
      huffbits = h->table[(h->ylen)*xl1+y];
      len = h->hlen[(h->ylen)*xl1+y];
      putbits(bs,huffbits,len);
      if (h->linbits) {
        putbits(bs,linbitsX,h->linbits);
      }
    }
  }
  else  { /* ((x < h->xlen) && (y>=h->ylen)) */
    huffbits = h->table[(h->ylen)*x+yl1];
    len = h->hlen[(h->ylen)*x+yl1];
    putbits(bs,huffbits,len);
    linbitsY = y-yl1;
    if (linbitsY > h->linmax) {
      linbitsY = h->linmax;
    };
    if (h->linbits) {
       putbits(bs,linbitsY,h->linbits);
    }
  }
}