GNU Radio 2.x: gr_circular_file.h Source File

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# gr_circular_file.h

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    00001 /* -*- c++ -*- */
    00002 /*
    00003  * Copyright 2002 Free Software Foundation, Inc.
    00004  *
    00005  * This file is part of GNU Radio
    00006  *
    00007  * GNU Radio is free software; you can redistribute it and/or modify
    00008  * it under the terms of the GNU General Public License as published by
    00009  * the Free Software Foundation; either version 2, or (at your option)
    00010  * any later version.
    00011  *
    00012  * GNU Radio is distributed in the hope that it will be useful,
    00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00015  * GNU General Public License for more details.
    00016  *
    00017  * You should have received a copy of the GNU General Public License
    00018  * along with GNU Radio; see the file COPYING.  If not, write to
    00019  * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    00020  * Boston, MA 02111-1307, USA.
    00021  */
    00022
    00023 #ifndef _GR_CIRCULAR_FILE_H_
    00024 #define _GR_CIRCULAR_FILE_H_
    00025
    00026 /*
    00027  * writes input data into a circular buffer on disk.
    00028  *
    00029  * the file contains a fixed header:
    00030  *   0x0000:    int32 magic (0xEB021026)
    00031  *   0x0004:    int32 size in bytes of header (constant 4096)
    00032  *   0x0008:    int32 size in bytes of circular buffer (not including header)
    00033  *   0x000C:    int32 file offset to beginning of circular buffer
    00034  *   0x0010:    int32 byte offset from beginning of circular buffer to
    00035  *                    current start of data
    00036  *
    00037  */
    00038 class gr_circular_file {
    00039   int            d_fd;
    00040   int           *d_header;
    00041   unsigned char *d_buffer;
    00042   int            d_mapped_size;
    00043   int            d_bytes_read;
    00044
    00045 public:
    00046   gr_circular_file (const char *filename, bool writable = false, int size = 0);
    00047   ~gr_circular_file ();
    00048
    00049   bool write (void *data, int nbytes);
    00050
    00051   // returns # of bytes actually read or 0 if end of buffer, or -1 on error.
    00052   int read (void *data, int nbytes);
    00053
    00054   // reset read pointer to beginning of buffer.
    00055   void reset_read_pointer ();
    00056 };
    00057
    00058 #endif /* _GR_CIRCULAR_FILE_H_ */