summaryrefslogtreecommitdiff
path: root/gr-digital/include/digital_framer_sink_1.h
diff options
context:
space:
mode:
Diffstat (limited to 'gr-digital/include/digital_framer_sink_1.h')
-rw-r--r--gr-digital/include/digital_framer_sink_1.h107
1 files changed, 107 insertions, 0 deletions
diff --git a/gr-digital/include/digital_framer_sink_1.h b/gr-digital/include/digital_framer_sink_1.h
new file mode 100644
index 000000000..bb82bf5a7
--- /dev/null
+++ b/gr-digital/include/digital_framer_sink_1.h
@@ -0,0 +1,107 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2005,2006,2012 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 INCLUDED_GR_FRAMER_SINK_1_H
+#define INCLUDED_GR_FRAMER_SINK_1_H
+
+#include <digital_api.h>
+#include <gr_sync_block.h>
+#include <gr_msg_queue.h>
+
+class digital_framer_sink_1;
+typedef boost::shared_ptr<digital_framer_sink_1> digital_framer_sink_1_sptr;
+
+DIGITAL_API digital_framer_sink_1_sptr
+digital_make_framer_sink_1(gr_msg_queue_sptr target_queue);
+
+/*!
+ * \brief Given a stream of bits and access_code flags, assemble packets.
+ * \ingroup sink_blk
+ *
+ * input: stream of bytes from gr_correlate_access_code_bb
+ * output: none. Pushes assembled packet into target queue
+ *
+ * The framer expects a fixed length header of 2 16-bit shorts
+ * containing the payload length, followed by the payload. If the
+ * 2 16-bit shorts are not identical, this packet is ignored. Better
+ * algs are welcome.
+ *
+ * The input data consists of bytes that have two bits used.
+ * Bit 0, the LSB, contains the data bit.
+ * Bit 1 if set, indicates that the corresponding bit is the
+ * the first bit of the packet. That is, this bit is the first
+ * one after the access code.
+ */
+class DIGITAL_API digital_framer_sink_1 : public gr_sync_block
+{
+ friend DIGITAL_API digital_framer_sink_1_sptr
+ digital_make_framer_sink_1(gr_msg_queue_sptr target_queue);
+
+ private:
+ enum state_t {STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER};
+
+ static const int MAX_PKT_LEN = 4096;
+ static const int HEADERBITLEN = 32;
+
+ gr_msg_queue_sptr d_target_queue; // where to send the packet when received
+ state_t d_state;
+ unsigned int d_header; // header bits
+ int d_headerbitlen_cnt; // how many so far
+
+ unsigned char d_packet[MAX_PKT_LEN]; // assembled payload
+ unsigned char d_packet_byte; // byte being assembled
+ int d_packet_byte_index; // which bit of d_packet_byte we're working on
+ int d_packetlen; // length of packet
+ int d_packet_whitener_offset; // offset into whitener string to use
+ int d_packetlen_cnt; // how many so far
+
+ protected:
+ digital_framer_sink_1(gr_msg_queue_sptr target_queue);
+
+ void enter_search();
+ void enter_have_sync();
+ void enter_have_header(int payload_len, int whitener_offset);
+
+ bool header_ok()
+ {
+ // confirm that two copies of header info are identical
+ return ((d_header >> 16) ^ (d_header & 0xffff)) == 0;
+ }
+
+ void header_payload(int *len, int *offset)
+ {
+ // header consists of two 16-bit shorts in network byte order
+ // payload length is lower 12 bits
+ // whitener offset is upper 4 bits
+ *len = (d_header >> 16) & 0x0fff;
+ *offset = (d_header >> 28) & 0x000f;
+ }
+
+ public:
+ ~digital_framer_sink_1();
+
+ int work(int noutput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items);
+};
+
+#endif /* INCLUDED_GR_FRAMER_SINK_1_H */