Function mi_bbitmap_bsr_inv

system/lib/mimalloc/src/bitmap.c:1574–1599

}

bool mi_bbitmap_bsr_inv(mi_bbitmap_t* bbitmap, size_t* idx) {
  const size_t chunk_count = mi_bbitmap_chunk_count(bbitmap);
  const size_t chunkmap_max = _mi_divide_up(chunk_count, MI_BFIELD_BITS);
  size_t skip_at_top = chunk_count % MI_BFIELD_BITS;
  for (size_t i = chunkmap_max; i > 0; ) {
    i--;
    mi_bfield_t cmap = mi_atomic_load_relaxed(&bbitmap->chunkmap.bfields[i]);
    size_t cmap_idx;
    // don't consider top 0 bits; set those to 1 here
    if (skip_at_top > 0) {
      const size_t mask_top = (~mi_bfield_zero()) << (MI_BFIELD_BITS - skip_at_top);
      skip_at_top = 0;   // only for the first iteration
      cmap |= mask_top;
    }
    if (mi_bsr(~cmap, &cmap_idx)) {
      // highest chunk
      const size_t chunk_idx = i*MI_BFIELD_BITS + cmap_idx;
      size_t cidx;
      if (mi_bchunk_bsr_inv(&bbitmap->chunks[chunk_idx], &cidx)) {
        *idx = (chunk_idx * MI_BCHUNK_BITS) + cidx;
        return true;
      }
    }
  }
  return false;
}


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