1 /* -*- c++ -*- */ 2 /* 3 * Copyright 2002,2013 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 <gnuradio/api.h> 27 28 namespace gr { 29 30 /* 31 * writes input data into a circular buffer on disk. 32 * 33 * the file contains a fixed header: 34 * 0x0000: int32 magic (0xEB021026) 35 * 0x0004: int32 size in bytes of header (constant 4096) 36 * 0x0008: int32 size in bytes of circular buffer (not including header) 37 * 0x000C: int32 file offset to beginning of circular buffer 38 * 0x0010: int32 byte offset from beginning of circular buffer to 39 * current start of data 40 */ 41 class GR_RUNTIME_API circular_file 42 { 43 private: 44 int d_fd; 45 int* d_header; 46 unsigned char* d_buffer; 47 int d_mapped_size; 48 int d_bytes_read; 49 50 public: 51 circular_file(const char* filename, bool writable = false, int size = 0); 52 ~circular_file(); 53 54 bool write(void* data, int nbytes); 55 56 // returns # of bytes actually read or 0 if end of buffer, or -1 on error. 57 int read(void* data, int nbytes); 58 59 // reset read pointer to beginning of buffer. 60 void reset_read_pointer(); 61 }; 62 63 } /* namespace gr */ 64 65 #endif /* GR_CIRCULAR_FILE_H */ 66