Function choosePivot

third-party/lua-5.5.0/src/ltablib.c:330–335

** Choose an element in the middle (2nd-3th quarters) of [lo,up] ** "randomized" by 'rnd' */

** "randomized" by 'rnd'
*/
static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
  IdxT r4 = (up - lo) / 4;  /* range/4 */
  IdxT p = (rnd ^ lo ^ up) % (r4 * 2) + (lo + r4);
  lua_assert(lo + r4 <= p && p <= up - r4);
  return p;
}


/*