GNU Radio 3.6.4 C++ API
gr_circular_file.h
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1 /* -*- c++ -*- */
2 /*
3  * Copyright 2002 Free Software Foundation, Inc.
4  *
5  * This file is part of GNU Radio
6  *
7  * GNU Radio is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 3, or (at your option)
10  * any later version.
11  *
12  * GNU Radio is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with GNU Radio; see the file COPYING. If not, write to
19  * the Free Software Foundation, Inc., 51 Franklin Street,
20  * Boston, MA 02110-1301, USA.
21  */
22 
23 #ifndef _GR_CIRCULAR_FILE_H_
24 #define _GR_CIRCULAR_FILE_H_
25 
26 #include <gr_core_api.h>
27 
28 /*
29  * writes input data into a circular buffer on disk.
30  *
31  * the file contains a fixed header:
32  * 0x0000: int32 magic (0xEB021026)
33  * 0x0004: int32 size in bytes of header (constant 4096)
34  * 0x0008: int32 size in bytes of circular buffer (not including header)
35  * 0x000C: int32 file offset to beginning of circular buffer
36  * 0x0010: int32 byte offset from beginning of circular buffer to
37  * current start of data
38  *
39  */
41  int d_fd;
42  int *d_header;
43  unsigned char *d_buffer;
44  int d_mapped_size;
45  int d_bytes_read;
46 
47 public:
48  gr_circular_file (const char *filename, bool writable = false, int size = 0);
49  ~gr_circular_file ();
50 
51  bool write (void *data, int nbytes);
52 
53  // returns # of bytes actually read or 0 if end of buffer, or -1 on error.
54  int read (void *data, int nbytes);
55 
56  // reset read pointer to beginning of buffer.
57  void reset_read_pointer ();
58 };
59 
60 #endif /* _GR_CIRCULAR_FILE_H_ */