Function _mi_bitmap_unclaim_across

3rd/mimalloc-2.0.9/src/bitmap.c:328–347

Set `count` bits at `bitmap_idx` to 0 atomically Returns `true` if all `count` bits were 1 previously.

// Set `count` bits at `bitmap_idx` to 0 atomically
// Returns `true` if all `count` bits were 1 previously.
bool _mi_bitmap_unclaim_across(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx) {
  size_t idx = mi_bitmap_index_field(bitmap_idx);
  size_t pre_mask;
  size_t mid_mask;
  size_t post_mask;
  size_t mid_count = mi_bitmap_mask_across(bitmap_idx, bitmap_fields, count, &pre_mask, &mid_mask, &post_mask);
  bool all_one = true;
  mi_bitmap_field_t* field = &bitmap[idx];
  size_t prev = mi_atomic_and_acq_rel(field++, ~pre_mask);
  if ((prev & pre_mask) != pre_mask) all_one = false;
  while(mid_count-- > 0) {
    prev = mi_atomic_and_acq_rel(field++, ~mid_mask);
    if ((prev & mid_mask) != mid_mask) all_one = false;
  }
  if (post_mask!=0) {
    prev = mi_atomic_and_acq_rel(field, ~post_mask);
    if ((prev & post_mask) != post_mask) all_one = false;
  }
  return all_one;
}

// Set `count` bits at `bitmap_idx` to 1 atomically
// Returns `true` if all `count` bits were 0 previously. `any_zero` is `true` if there was at least one zero bit.