dlib C++ Library - bit_stream_kernel_1.cpp

    // Copyright (C) 2003  Davis E. King (davisking@users.sourceforge.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_BIT_STREAM_KERNEL_1_CPp_
    #define DLIB_BIT_STREAM_KERNEL_1_CPp_

    #include "bit_stream_kernel_1.h"
    #include "../algs.h"

    #include <iostream>

    namespace dlib
    {

        inline void swap (
            bit_stream_kernel_1& a,
            bit_stream_kernel_1& b
        ) { a.swap(b); }

    // ----------------------------------------------------------------------------------------
    // ----------------------------------------------------------------------------------------
        // member function definitions
    // ----------------------------------------------------------------------------------------
    // ----------------------------------------------------------------------------------------

        void bit_stream_kernel_1::
        clear (
        )
        {
            if (write_mode)
            {
                write_mode = false;

                // flush output buffer
                if (buffer_size > 0)
                {
                    buffer <<= 8 - buffer_size;
                    osp->write(reinterpret_cast<char*>(&buffer),1);
                }
            }
            else
                read_mode = false;

        }

    // ----------------------------------------------------------------------------------------

        void bit_stream_kernel_1::
        set_input_stream (
            std::istream& is
        )
        {
            isp = &is;
            read_mode = true;

            buffer_size = 0;
        }

    // ----------------------------------------------------------------------------------------

        void bit_stream_kernel_1::
        set_output_stream (
            std::ostream& os
        )
        {
            osp = &os;
            write_mode = true;

            buffer_size = 0;
        }

    // ----------------------------------------------------------------------------------------

        void bit_stream_kernel_1::
        close (
        )
        {
            if (write_mode)
            {
                write_mode = false;

                // flush output buffer
                if (buffer_size > 0)
                {
                    buffer <<= 8 - buffer_size;
                    osp->write(reinterpret_cast<char*>(&buffer),1);
                }
            }
            else
                read_mode = false;
        }

    // ----------------------------------------------------------------------------------------

        bool bit_stream_kernel_1::
        is_in_write_mode (
        ) const
        {
            return write_mode;
        }

    // ----------------------------------------------------------------------------------------

        bool bit_stream_kernel_1::
        is_in_read_mode (
        ) const
        {
            return read_mode;
        }

    // ----------------------------------------------------------------------------------------

        void bit_stream_kernel_1::
        write (
            int bit
        )
        {
            // flush buffer if necessary
            if (buffer_size == 8)
            {
                buffer <<= 8 - buffer_size;
                if (osp->rdbuf()->sputn(reinterpret_cast<char*>(&buffer),1) == 0)
                {
                    throw std::ios_base::failure("error occured in the bit_stream object");
                }

                buffer_size = 0;
            }

            ++buffer_size;
            buffer <<= 1;
            buffer += static_cast<unsigned char>(bit);
        }

    // ----------------------------------------------------------------------------------------

        bool bit_stream_kernel_1::
        read (
            int& bit
        )
        {
            // get new byte if necessary
            if (buffer_size == 0)
            {
                if (isp->rdbuf()->sgetn(reinterpret_cast<char*>(&buffer), 1) == 0)
                {
                    // if we didn't read anything then return false
                    return false;
                }

                buffer_size = 8;
            }

            // put the most significant bit from buffer into bit
            bit = static_cast<int>(buffer >> 7);

            // shift out the bit that was just read
            buffer <<= 1;
            --buffer_size;

            return true;
        }

    // ----------------------------------------------------------------------------------------

        void bit_stream_kernel_1::
        swap (
            bit_stream_kernel_1& item
        )
        {

            std::istream*   isp_temp            = item.isp;
            std::ostream*   osp_temp            = item.osp;
            bool            write_mode_temp     = item.write_mode;
            bool            read_mode_temp      = item.read_mode;
            unsigned char   buffer_temp         = item.buffer;
            unsigned short  buffer_size_temp    = item.buffer_size;

            item.isp            = isp;
            item.osp            = osp;
            item.write_mode     = write_mode;
            item.read_mode      = read_mode;
            item.buffer         = buffer;
            item.buffer_size    = buffer_size;

            isp             = isp_temp;
            osp             = osp_temp;
            write_mode      = write_mode_temp;
            read_mode       = read_mode_temp;
            buffer          = buffer_temp;
            buffer_size     = buffer_size_temp;

        }

    // ----------------------------------------------------------------------------------------

    }
    #endif // DLIB_BIT_STREAM_KERNEL_1_CPp_