// Copyright 2018-2022 David Robillard <d@drobilla.net>
// Copyright 2006-2007 Chris Hamilton <chamilton@cs.dal.ca>
// SPDX-License-Identifier: GPL-2.0-or-later

#ifndef CHILBERT_DETAIL_BITVECINDEX_HPP
#define CHILBERT_DETAIL_BITVECINDEX_HPP

#include <cassert>
#include <climits>
#include <cstddef>

namespace chilbert {
namespace detail {

/// Index into a multi-rack bit vector
template<class BitVec>
struct BitVecIndex {
  using Rack = typename BitVec::Rack;

  static constexpr size_t bits_per_rack = sizeof(Rack) * CHAR_BIT;

  explicit BitVecIndex(const size_t bits)
    : rack{bits / bits_per_rack}
    , bit{bits - rack * bits_per_rack}
  {
    assert(bit < bits_per_rack);
  }

  size_t rack;
  size_t bit;
};

} // namespace detail
} // namespace chilbert

#endif