/* -*- c++ -*- */

/*

 * Copyright 2002 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_

/*

 * 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_circular_file {

  int                 d_fd;

  int                *d_header;

  unsigned char        *d_buffer;

  int                 d_mapped_size;

  int                 d_bytes_read;

public:

  gr_circular_file (const char *filename, bool writable = false, int size = 0);

  ~gr_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 ();

};

#endif /* _GR_CIRCULAR_FILE_H_ */