#include "coding/reader_writer_ops.hpp"

namespace rw_ops
{
  void Reverse(Reader const & src, Writer & dest)
  {
    // Read from end, reverse and write directly.

    size_t const bufSz = 1024;
    vector<uint8_t> buffer(bufSz);

    uint64_t pos = src.Size();
    while (pos > 0)
    {
      size_t const sz = pos > bufSz ? bufSz : pos;
      ASSERT_GREATER_OR_EQUAL(pos, sz, ());

      src.Read(pos - sz, &buffer[0], sz);

      std::reverse(buffer.begin(), buffer.begin() + sz);

      dest.Write(&buffer[0], sz);

      pos -= sz;
    }
  }
}