Function _mi_bitmap_claim

3rd/mimalloc-2.0.9/src/bitmap.c:153–162

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.

// 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.
bool _mi_bitmap_claim(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx, bool* any_zero) {
  const size_t idx = mi_bitmap_index_field(bitmap_idx);
  const size_t bitidx = mi_bitmap_index_bit_in_field(bitmap_idx);
  const size_t mask = mi_bitmap_mask_(count, bitidx);
  mi_assert_internal(bitmap_fields > idx); MI_UNUSED(bitmap_fields);
  //mi_assert_internal(any_zero != NULL || (bitmap[idx] & mask) == 0);
  size_t prev = mi_atomic_or_acq_rel(&bitmap[idx], mask);
  if (any_zero != NULL) *any_zero = ((prev & mask) != mask);
  return ((prev & mask) == 0);
}

// Returns `true` if all `count` bits were 1. `any_ones` is `true` if there was at least one bit set to one.
static bool mi_bitmap_is_claimedx(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx, bool* any_ones) {