unsigned char find_mask( unsigned char mask){
unsigned char a, b, *pBuff;
unsigned int var;
for(a = 0; a < 31; a++) {
  var = *pBuff;
  var <<= 8;
  pBuff += 1;
  var |= *pBuff;
  for(b = 0; b < 8; b++) {
    if (mask == (unsigned char)(var >> b)) return a*8+(8-b);//????
   }
 }
}