void s16_encode(unsigned int **_w, unsigned int **_p, unsigned int m)
{ 
int cnum[16] = {28, 21, 21, 21, 14, 9, 8, 7, 6, 6, 5, 5, 4, 3, 2, 1};
int cbits[16][28] = { {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
   {2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0},
   {1,1,1,1,1,1,1,2,2,2,2,2,2,2,1,1,1,1,1,1,1,0,0,0,0,0,0,0},
   {1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,0,0,0,0,0,0,0},
   {2,2,2,2,2,2,2,2,2,2,2,2,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {4,3,3,3,3,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {3,4,4,4,4,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {4,4,4,4,4,4,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {5,5,5,5,4,4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {4,4,5,5,5,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {6,6,6,5,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {5,5,6,6,6,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {7,7,7,7,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {10,9,9,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {14,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
   {28,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0} };

  unsigned int _k, _j, _m, _o;

  for (_k = 0; _k < 16; _k++) 
  { 
    (**_w) = _k<<28; 
    _m = (cnum[_k] < m)? cnum[_k]:m; 
    for (_j = 0, _o = 0; (_j < _m) && (*((*_p)+_j) < (1<<cbits[_k][_j])); ) 
    { 
      (**_w) += ((*((*_p)+_j))<<_o); 
      _o += cbits[_k][_j]; 
      _j++;
    } 
    if (_j == _m) 
    { 
      (*_p) += _m; 
      (*_w)++; 
      break; 
    } 
  } 
}


/* more optimized handcoded edition */

#define S16_DECODE(_w, _p)	\
{ \
  _k = (*_w)>>28; \
  switch(_k) \
  { \
    case 0: \
      *_p = (*_w) & 1;     _p++; \
      *_p = (*_w>>1) & 1;  _p++; \
      *_p = (*_w>>2) & 1;  _p++; \
      *_p = (*_w>>3) & 1;  _p++; \
      *_p = (*_w>>4) & 1;  _p++; \
      *_p = (*_w>>5) & 1;  _p++; \
      *_p = (*_w>>6) & 1;  _p++; \
      *_p = (*_w>>7) & 1;  _p++; \
      *_p = (*_w>>8) & 1;  _p++; \
      *_p = (*_w>>9) & 1;  _p++; \
      *_p = (*_w>>10) & 1;  _p++; \
      *_p = (*_w>>11) & 1;  _p++; \
      *_p = (*_w>>12) & 1;  _p++; \
      *_p = (*_w>>13) & 1;  _p++; \
      *_p = (*_w>>14) & 1;  _p++; \
      *_p = (*_w>>15) & 1;  _p++; \
      *_p = (*_w>>16) & 1;  _p++; \
      *_p = (*_w>>17) & 1;  _p++; \
      *_p = (*_w>>18) & 1;  _p++; \
      *_p = (*_w>>19) & 1;  _p++; \
      *_p = (*_w>>20) & 1;  _p++; \
      *_p = (*_w>>21) & 1;  _p++; \
      *_p = (*_w>>22) & 1;  _p++; \
      *_p = (*_w>>23) & 1;  _p++; \
      *_p = (*_w>>24) & 1;  _p++; \
      *_p = (*_w>>25) & 1;  _p++; \
      *_p = (*_w>>26) & 1;  _p++; \
      *_p = (*_w>>27) & 1;  _p++; \
      break; \
    case 1: \
      *_p = (*_w) & 3;     _p++; \
      *_p = (*_w>>2) & 3;  _p++; \
      *_p = (*_w>>4) & 3;  _p++; \
      *_p = (*_w>>6) & 3;  _p++; \
      *_p = (*_w>>8) & 3;  _p++; \
      *_p = (*_w>>10) & 3;  _p++; \
      *_p = (*_w>>12) & 3;  _p++; \
      *_p = (*_w>>14) & 1;  _p++; \
      *_p = (*_w>>15) & 1;  _p++; \
      *_p = (*_w>>16) & 1;  _p++; \
      *_p = (*_w>>17) & 1;  _p++; \
      *_p = (*_w>>18) & 1;  _p++; \
      *_p = (*_w>>19) & 1;  _p++; \
      *_p = (*_w>>20) & 1;  _p++; \
      *_p = (*_w>>21) & 1;  _p++; \
      *_p = (*_w>>22) & 1;  _p++; \
      *_p = (*_w>>23) & 1;  _p++; \
      *_p = (*_w>>24) & 1;  _p++; \
      *_p = (*_w>>25) & 1;  _p++; \
      *_p = (*_w>>26) & 1;  _p++; \
      *_p = (*_w>>27) & 1;  _p++; \
      break; \
    case 2: \
      *_p = (*_w) & 1;     _p++; \
      *_p = (*_w>>1) & 1;  _p++; \
      *_p = (*_w>>2) & 1;  _p++; \
      *_p = (*_w>>3) & 1;  _p++; \
      *_p = (*_w>>4) & 1;  _p++; \
      *_p = (*_w>>5) & 1;  _p++; \
      *_p = (*_w>>6) & 1;  _p++; \
      *_p = (*_w>>7) & 3;  _p++; \
      *_p = (*_w>>9) & 3;  _p++; \
      *_p = (*_w>>11) & 3;  _p++; \
      *_p = (*_w>>13) & 3;  _p++; \
      *_p = (*_w>>15) & 3;  _p++; \
      *_p = (*_w>>17) & 3;  _p++; \
      *_p = (*_w>>19) & 3;  _p++; \
      *_p = (*_w>>21) & 1;  _p++; \
      *_p = (*_w>>22) & 1;  _p++; \
      *_p = (*_w>>23) & 1;  _p++; \
      *_p = (*_w>>24) & 1;  _p++; \
      *_p = (*_w>>25) & 1;  _p++; \
      *_p = (*_w>>26) & 1;  _p++; \
      *_p = (*_w>>27) & 1;  _p++; \
      break; \
    case 3: \
      *_p = (*_w) & 1;     _p++; \
      *_p = (*_w>>1) & 1;  _p++; \
      *_p = (*_w>>2) & 1;  _p++; \
      *_p = (*_w>>3) & 1;  _p++; \
      *_p = (*_w>>4) & 1;  _p++; \
      *_p = (*_w>>5) & 1;  _p++; \
      *_p = (*_w>>6) & 1;  _p++; \
      *_p = (*_w>>7) & 1;  _p++; \
      *_p = (*_w>>8) & 1;  _p++; \
      *_p = (*_w>>9) & 1;  _p++; \
      *_p = (*_w>>10) & 1;  _p++; \
      *_p = (*_w>>11) & 1;  _p++; \
      *_p = (*_w>>12) & 1;  _p++; \
      *_p = (*_w>>13) & 1;  _p++; \
      *_p = (*_w>>14) & 3;  _p++; \
      *_p = (*_w>>16) & 3;  _p++; \
      *_p = (*_w>>18) & 3;  _p++; \
      *_p = (*_w>>20) & 3;  _p++; \
      *_p = (*_w>>22) & 3;  _p++; \
      *_p = (*_w>>24) & 3;  _p++; \
      *_p = (*_w>>26) & 3;  _p++; \
      break; \
    case 4: \
      *_p = (*_w) & 3;     _p++; \
      *_p = (*_w>>2) & 3;  _p++; \
      *_p = (*_w>>4) & 3;  _p++; \
      *_p = (*_w>>6) & 3;  _p++; \
      *_p = (*_w>>8) & 3;  _p++; \
      *_p = (*_w>>10) & 3;  _p++; \
      *_p = (*_w>>12) & 3;  _p++; \
      *_p = (*_w>>14) & 3;  _p++; \
      *_p = (*_w>>16) & 3;  _p++; \
      *_p = (*_w>>18) & 3;  _p++; \
      *_p = (*_w>>20) & 3;  _p++; \
      *_p = (*_w>>22) & 3;  _p++; \
      *_p = (*_w>>24) & 3;  _p++; \
      *_p = (*_w>>26) & 3;  _p++; \
      break; \
    case 5: \
      *_p = (*_w) & 15;     _p++; \
      *_p = (*_w>>4) & 7;  _p++; \
      *_p = (*_w>>7) & 7;  _p++; \
      *_p = (*_w>>10) & 7;  _p++; \
      *_p = (*_w>>13) & 7;  _p++; \
      *_p = (*_w>>16) & 7;  _p++; \
      *_p = (*_w>>19) & 7;  _p++; \
      *_p = (*_w>>22) & 7;  _p++; \
      *_p = (*_w>>25) & 7;  _p++; \
      break; \
    case 6: \
      *_p = (*_w) & 7;     _p++; \
      *_p = (*_w>>3) & 15;  _p++; \
      *_p = (*_w>>7) & 15;  _p++; \
      *_p = (*_w>>11) & 15;  _p++; \
      *_p = (*_w>>15) & 15;  _p++; \
      *_p = (*_w>>19) & 7;  _p++; \
      *_p = (*_w>>22) & 7;  _p++; \
      *_p = (*_w>>25) & 7;  _p++; \
      break; \
    case 7: \
      *_p = (*_w) & 15;     _p++; \
      *_p = (*_w>>4) & 15;  _p++; \
      *_p = (*_w>>8) & 15;  _p++; \
      *_p = (*_w>>12) & 15;  _p++; \
      *_p = (*_w>>16) & 15;  _p++; \
      *_p = (*_w>>20) & 15;  _p++; \
      *_p = (*_w>>24) & 15;  _p++; \
      break; \
    case 8: \
      *_p = (*_w) & 31;     _p++; \
      *_p = (*_w>>5) & 31;  _p++; \
      *_p = (*_w>>10) & 31;  _p++; \
      *_p = (*_w>>15) & 31;  _p++; \
      *_p = (*_w>>20) & 15;  _p++; \
      *_p = (*_w>>24) & 15;  _p++; \
      break; \
    case 9: \
      *_p = (*_w) & 15;     _p++; \
      *_p = (*_w>>4) & 15;  _p++; \
      *_p = (*_w>>8) & 31;  _p++; \
      *_p = (*_w>>13) & 31;  _p++; \
      *_p = (*_w>>18) & 31;  _p++; \
      *_p = (*_w>>23) & 31;  _p++; \
      break; \
    case 10: \
      *_p = (*_w) & 63;     _p++; \
      *_p = (*_w>>6) & 63;  _p++; \
      *_p = (*_w>>12) & 63;  _p++; \
      *_p = (*_w>>18) & 31;  _p++; \
      *_p = (*_w>>23) & 31;  _p++; \
      break; \
    case 11: \
      *_p = (*_w) & 31;     _p++; \
      *_p = (*_w>>5) & 31;  _p++; \
      *_p = (*_w>>10) & 63;  _p++; \
      *_p = (*_w>>16) & 63;  _p++; \
      *_p = (*_w>>22) & 63;  _p++; \
      break; \
    case 12: \
      *_p = (*_w) & 127;     _p++; \
      *_p = (*_w>>7) & 127;  _p++; \
      *_p = (*_w>>14) & 127;  _p++; \
      *_p = (*_w>>21) & 127;  _p++; \
      break; \
    case 13: \
      *_p = (*_w) & 1023;     _p++; \
      *_p = (*_w>>10) & 511;  _p++; \
      *_p = (*_w>>19) & 511;  _p++; \
      break; \
    case 14: \
      *_p = (*_w) & 16383;     _p++; \
      *_p = (*_w>>14) & 16383;  _p++; \
      break; \
    case 15: \
      *_p = (*_w) & ((1<<28)-1);     _p++; \
      break; \
  }\
  _w++; \
}