Function mi_bbitmap_try_clearNC

system/lib/mimalloc/src/bitmap.c:1702–1717

Try to clear `n` bits at `idx` where `n <= MI_BCHUNK_BITS`.

// Try to clear `n` bits at `idx` where `n <= MI_BCHUNK_BITS`.
bool mi_bbitmap_try_clearNC(mi_bbitmap_t* bbitmap, size_t idx, size_t n) {
  mi_assert_internal(n>0);
  mi_assert_internal(n<=MI_BCHUNK_BITS);
  mi_assert_internal(idx + n <= mi_bbitmap_max_bits(bbitmap));

  const size_t chunk_idx = idx / MI_BCHUNK_BITS;
  const size_t cidx = idx % MI_BCHUNK_BITS;
  mi_assert_internal(cidx + n <= MI_BCHUNK_BITS);  // don't cross chunks (for now)
  mi_assert_internal(chunk_idx < mi_bbitmap_chunk_count(bbitmap));
  if (cidx + n > MI_BCHUNK_BITS) return false;
  bool maybe_all_clear = false;
  const bool cleared = mi_bchunk_try_clearN(&bbitmap->chunks[chunk_idx], cidx, n, &maybe_all_clear);
  if (cleared && maybe_all_clear) { mi_bbitmap_chunkmap_try_clear(bbitmap, chunk_idx); }
  // note: we don't set the size class for an explicit try_clearN (only used by purging)
  return cleared;
}