Branchless comparison

main.mojo

fn compare(s1: DTypePointer[DType.uint8], s2: DTypePointer[DType.uint8], count: Int)->Int:
  var result = 0
  var i = 0
  while i < count:
    var s1i = s1[i]
    var s2i = s2[i]
    var smaller = s1i < s2i
    var bigger = s1i > s2i
    i += 1 + count * int(smaller or bigger)
    result = -1 * int(smaller) + 1 * int(bigger)
  return result

def main():
  var a = DTypePointer[DType.uint8].alloc(2)
  var b = DTypePointer[DType.uint8].alloc(2)
  a[0] = 20
  a[1] = 30
  b[0] = 20
  b[1] = 40
  print(compare(a, b, 2))
  print(compare(b, a, 2))
  print(compare(a, b, 1))
  print(compare(b, a, 1))
  print(compare(a, a, 2))