Function luaO_int2fb

depends/lua/src/lobject.c:41–53

** converts an integer to a "floating point byte", represented as ** (eeeeexxx), where the real value is (1xxx) * 2^(eeeee - 1) if ** eeeee != 0 and (xxx) otherwise. */

** eeeee != 0 and (xxx) otherwise.
*/
int luaO_int2fb (unsigned int x) {
  int e = 0;  /* exponent */
  if (x < 8) return x;
  while (x >= (8 << 4)) {  /* coarse steps */
    x = (x + 0xf) >> 4;  /* x = ceil(x / 16) */
    e += 4;
  }
  while (x >= (8 << 1)) {  /* fine steps */
    x = (x + 1) >> 1;  /* x = ceil(x / 2) */
    e++;
  }
  return ((e+1) << 3) | (cast_int(x) - 8);
}


/* converts back */