/*

Copyright (c) 2020, Arvid Norberg

All rights reserved.

You may use, distribute and modify this code under the terms of the BSD license,

see LICENSE file.

*/

struct read_bits

{

  read_bits(std::uint8_t const* d, std::size_t s)

    : m_data(d), m_size(s)

  {}

  int read(int bits)

  {

    if (m_size == 0) return 0;

    int ret = 0;

    while (bits > 0 && m_size > 0)

    {

      int const bits_to_copy = std::min(8 - m_bit, bits);

      ret <<= bits_to_copy;

      ret |= ((*m_data) >> m_bit) & ((1 << bits_to_copy) - 1);

      m_bit += bits_to_copy;

      bits -= bits_to_copy;

      if (m_bit == 8)

      {

        --m_size;

        ++m_data;

        m_bit = 0;

      }

    }

    return ret;

  }

private:

  std::uint8_t const* m_data;

  std::size_t m_size;

  int m_bit = 0;

};