Function mi_slice_bin8

3rd/mimalloc-2.0.9/src/segment.c:177–185

// Use bit scan forward to quickly find the first zero bit if it is available

static inline size_t mi_slice_bin8(size_t slice_count) {
  if (slice_count<=1) return slice_count;
  mi_assert_internal(slice_count <= MI_SLICES_PER_SEGMENT);
  slice_count--;
  size_t s = mi_bsr(slice_count);  // slice_count > 1
  if (s <= 2) return slice_count + 1;
  size_t bin = ((s << 2) | ((slice_count >> (s - 2))&0x03)) - 4;
  return bin;
}

static inline size_t mi_slice_bin(size_t slice_count) {
  mi_assert_internal(slice_count*MI_SEGMENT_SLICE_SIZE <= MI_SEGMENT_SIZE);