3 * Copyright 2005,2006 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
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)
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.
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.
23 #ifndef INCLUDED_GR_FRAMER_SINK_1_H
24 #define INCLUDED_GR_FRAMER_SINK_1_H
26 #include <gr_sync_block.h>
27 #include <gr_msg_queue.h>
29 class gr_framer_sink_1;
30 typedef boost::shared_ptr<gr_framer_sink_1> gr_framer_sink_1_sptr;
33 gr_make_framer_sink_1 (gr_msg_queue_sptr target_queue);
36 * \brief Given a stream of bits and access_code flags, assemble packets.
39 * input: stream of bytes from gr_correlate_access_code_bb
40 * output: none. Pushes assembled packet into target queue
42 * The framer expects a fixed length header of 2 16-bit shorts
43 * containing the payload length, followed by the payload. If the
44 * 2 16-bit shorts are not identical, this packet is ignored. Better
47 * The input data consists of bytes that have two bits used.
48 * Bit 0, the LSB, contains the data bit.
49 * Bit 1 if set, indicates that the corresponding bit is the
50 * the first bit of the packet. That is, this bit is the first
51 * one after the access code.
53 class gr_framer_sink_1 : public gr_sync_block
55 friend gr_framer_sink_1_sptr
56 gr_make_framer_sink_1 (gr_msg_queue_sptr target_queue);
59 enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};
61 static const int MAX_PKT_LEN = 4096;
62 static const int HEADERBITLEN = 32;
64 gr_msg_queue_sptr d_target_queue; // where to send the packet when received
66 unsigned int d_header; // header bits
67 int d_headerbitlen_cnt; // how many so far
69 unsigned char d_packet[MAX_PKT_LEN]; // assembled payload
70 unsigned char d_packet_byte; // byte being assembled
71 int d_packet_byte_index; // which bit of d_packet_byte we're working on
72 int d_packetlen; // length of packet
73 int d_packet_whitener_offset; // offset into whitener string to use
74 int d_packetlen_cnt; // how many so far
77 gr_framer_sink_1(gr_msg_queue_sptr target_queue);
80 void enter_have_sync();
81 void enter_have_header(int payload_len, int whitener_offset);
85 // confirm that two copies of header info are identical
86 return ((d_header >> 16) ^ (d_header & 0xffff)) == 0;
89 void header_payload(int *len, int *offset)
91 // header consists of two 16-bit shorts in network byte order
92 // payload length is lower 12 bits
93 // whitener offset is upper 4 bits
94 *len = (d_header >> 16) & 0x0fff;
95 *offset = (d_header >> 28) & 0x000f;
101 int work(int noutput_items,
102 gr_vector_const_void_star &input_items,
103 gr_vector_void_star &output_items);
106 #endif /* INCLUDED_GR_FRAMER_SINK_1_H */