/* -*- c++ -*- */ /* * Copyright 2004,2010,2012 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. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include <digital_packet_sink.h> #include <gr_io_signature.h> #include <cstdio> #include <errno.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdexcept> #include <gr_count_bits.h> #include <string.h> #define VERBOSE 0 static const int DEFAULT_THRESHOLD = 12; // detect access code with up to DEFAULT_THRESHOLD bits wrong inline void digital_packet_sink::enter_search() { if (VERBOSE) fprintf(stderr, "@ enter_search\n"); d_state = STATE_SYNC_SEARCH; d_shift_reg = 0; } inline void digital_packet_sink::enter_have_sync() { if (VERBOSE) fprintf(stderr, "@ enter_have_sync\n"); d_state = STATE_HAVE_SYNC; d_header = 0; d_headerbitlen_cnt = 0; } inline void digital_packet_sink::enter_have_header(int payload_len) { if (VERBOSE) fprintf(stderr, "@ enter_have_header (payload_len = %d)\n", payload_len); d_state = STATE_HAVE_HEADER; d_packetlen = payload_len; d_packetlen_cnt = 0; d_packet_byte = 0; d_packet_byte_index = 0; } digital_packet_sink_sptr digital_make_packet_sink (const std::vector<unsigned char>& sync_vector, gr_msg_queue_sptr target_queue, int threshold) { return gnuradio::get_initial_sptr(new digital_packet_sink (sync_vector, target_queue, threshold)); } digital_packet_sink::digital_packet_sink (const std::vector<unsigned char>& sync_vector, gr_msg_queue_sptr target_queue, int threshold) : gr_sync_block ("packet_sink", gr_make_io_signature (1, 1, sizeof(float)), gr_make_io_signature (0, 0, 0)), d_target_queue(target_queue), d_threshold(threshold == -1 ? DEFAULT_THRESHOLD : threshold) { d_sync_vector = 0; for(int i=0;i<8;i++){ d_sync_vector <<= 8; d_sync_vector |= sync_vector[i]; } enter_search(); } digital_packet_sink::~digital_packet_sink () { } int digital_packet_sink::work (int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items) { float *inbuf = (float *) input_items[0]; int count=0; if (VERBOSE) fprintf(stderr,">>> Entering state machine\n"),fflush(stderr); while (count<noutput_items) { switch(d_state) { case STATE_SYNC_SEARCH: // Look for sync vector if (VERBOSE) fprintf(stderr,"SYNC Search, noutput=%d\n",noutput_items),fflush(stderr); while (count < noutput_items) { if(slice(inbuf[count++])) d_shift_reg = (d_shift_reg << 1) | 1; else d_shift_reg = d_shift_reg << 1; // Compute popcnt of putative sync vector if(gr_count_bits64 (d_shift_reg ^ d_sync_vector) <= d_threshold) { // Found it, set up for header decode enter_have_sync(); break; } } break; case STATE_HAVE_SYNC: if (VERBOSE) fprintf(stderr,"Header Search bitcnt=%d, header=0x%08x\n", d_headerbitlen_cnt, d_header), fflush(stderr); while (count < noutput_items) { // Shift bits one at a time into header if(slice(inbuf[count++])) d_header = (d_header << 1) | 1; else d_header = d_header << 1; if (++d_headerbitlen_cnt == HEADERBITLEN) { if (VERBOSE) fprintf(stderr, "got header: 0x%08x\n", d_header); // we have a full header, check to see if it has been received properly if (header_ok()){ int payload_len = header_payload_len(); if (payload_len <= MAX_PKT_LEN) // reasonable? enter_have_header(payload_len); // yes. else enter_search(); // no. } else enter_search(); // no. break; // we're in a new state } } break; case STATE_HAVE_HEADER: if (VERBOSE) fprintf(stderr,"Packet Build\n"),fflush(stderr); while (count < noutput_items) { // shift bits into bytes of packet one at a time if(slice(inbuf[count++])) d_packet_byte = (d_packet_byte << 1) | 1; else d_packet_byte = d_packet_byte << 1; if (d_packet_byte_index++ == 7) { // byte is full so move to next byte d_packet[d_packetlen_cnt++] = d_packet_byte; d_packet_byte_index = 0; if (d_packetlen_cnt == d_packetlen){ // packet is filled // build a message gr_message_sptr msg = gr_make_message(0, 0, 0, d_packetlen_cnt); memcpy(msg->msg(), d_packet, d_packetlen_cnt); d_target_queue->insert_tail(msg); // send it msg.reset(); // free it up enter_search(); break; } } } break; default: assert(0); } // switch } // while return noutput_items; }