/* -*- c++ -*- */
/*
 * Copyright 2002,2013 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 *
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifndef GR_CIRCULAR_FILE_H
#define GR_CIRCULAR_FILE_H

#include <gnuradio/api.h>

namespace gr {

/*
 * writes input data into a circular buffer on disk.
 *
 * the file contains a fixed header:
 *   0x0000: int32 magic (0xEB021026)
 *   0x0004: int32 size in bytes of header (constant 4096)
 *   0x0008: int32 size in bytes of circular buffer (not including header)
 *   0x000C: int32 file offset to beginning of circular buffer
 *   0x0010: int32 byte offset from beginning of circular buffer to
 *                 current start of data
 */
class GR_RUNTIME_API circular_file
{
private:
    int d_fd;
    int* d_header;
    unsigned char* d_buffer;
    int d_mapped_size;
    int d_bytes_read;

public:
    circular_file(const char* filename, bool writable = false, int size = 0);
    ~circular_file();

    bool write(void* data, int nbytes);

    // returns # of bytes actually read or 0 if end of buffer, or -1 on error.
    int read(void* data, int nbytes);

    // reset read pointer to beginning of buffer.
    void reset_read_pointer();
};

} /* namespace gr */

#endif /* GR_CIRCULAR_FILE_H */
