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Diffstat (limited to 'gr-digital/lib/digital_ofdm_frame_sink.cc')
| -rw-r--r-- | gr-digital/lib/digital_ofdm_frame_sink.cc | 405 |
1 files changed, 405 insertions, 0 deletions
diff --git a/gr-digital/lib/digital_ofdm_frame_sink.cc b/gr-digital/lib/digital_ofdm_frame_sink.cc new file mode 100644 index 000000000..f8fb1bbb1 --- /dev/null +++ b/gr-digital/lib/digital_ofdm_frame_sink.cc @@ -0,0 +1,405 @@ +/* -*- c++ -*- */ +/* + * Copyright 2007,2008,2010,2011 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_ofdm_frame_sink.h> +#include <gr_io_signature.h> +#include <gr_expj.h> +#include <gr_math.h> +#include <math.h> +#include <cstdio> +#include <stdexcept> +#include <iostream> +#include <string.h> + +#define VERBOSE 0 + +inline void +digital_ofdm_frame_sink::enter_search() +{ + if (VERBOSE) + fprintf(stderr, "@ enter_search\n"); + + d_state = STATE_SYNC_SEARCH; + +} + +inline void +digital_ofdm_frame_sink::enter_have_sync() +{ + if (VERBOSE) + fprintf(stderr, "@ enter_have_sync\n"); + + d_state = STATE_HAVE_SYNC; + + // clear state of demapper + d_byte_offset = 0; + d_partial_byte = 0; + + d_header = 0; + d_headerbytelen_cnt = 0; + + // Resetting PLL + d_freq = 0.0; + d_phase = 0.0; + fill(d_dfe.begin(), d_dfe.end(), gr_complex(1.0,0.0)); +} + +inline void +digital_ofdm_frame_sink::enter_have_header() +{ + d_state = STATE_HAVE_HEADER; + + // header consists of two 16-bit shorts in network byte order + // payload length is lower 12 bits + // whitener offset is upper 4 bits + d_packetlen = (d_header >> 16) & 0x0fff; + d_packet_whitener_offset = (d_header >> 28) & 0x000f; + d_packetlen_cnt = 0; + + if (VERBOSE) + fprintf(stderr, "@ enter_have_header (payload_len = %d) (offset = %d)\n", + d_packetlen, d_packet_whitener_offset); +} + + +unsigned char digital_ofdm_frame_sink::slicer(const gr_complex x) +{ + unsigned int table_size = d_sym_value_out.size(); + unsigned int min_index = 0; + float min_euclid_dist = norm(x - d_sym_position[0]); + float euclid_dist = 0; + + for (unsigned int j = 1; j < table_size; j++){ + euclid_dist = norm(x - d_sym_position[j]); + if (euclid_dist < min_euclid_dist){ + min_euclid_dist = euclid_dist; + min_index = j; + } + } + return d_sym_value_out[min_index]; +} + +unsigned int digital_ofdm_frame_sink::demapper(const gr_complex *in, + unsigned char *out) +{ + unsigned int i=0, bytes_produced=0; + gr_complex carrier; + + carrier=gr_expj(d_phase); + + gr_complex accum_error = 0.0; + //while(i < d_occupied_carriers) { + while(i < d_subcarrier_map.size()) { + if(d_nresid > 0) { + d_partial_byte |= d_resid; + d_byte_offset += d_nresid; + d_nresid = 0; + d_resid = 0; + } + + //while((d_byte_offset < 8) && (i < d_occupied_carriers)) { + while((d_byte_offset < 8) && (i < d_subcarrier_map.size())) { + //gr_complex sigrot = in[i]*carrier*d_dfe[i]; + gr_complex sigrot = in[d_subcarrier_map[i]]*carrier*d_dfe[i]; + + if(d_derotated_output != NULL){ + d_derotated_output[i] = sigrot; + } + + unsigned char bits = slicer(sigrot); + + gr_complex closest_sym = d_sym_position[bits]; + + accum_error += sigrot * conj(closest_sym); + + // FIX THE FOLLOWING STATEMENT + if (norm(sigrot)> 0.001) d_dfe[i] += d_eq_gain*(closest_sym/sigrot-d_dfe[i]); + + i++; + + if((8 - d_byte_offset) >= d_nbits) { + d_partial_byte |= bits << (d_byte_offset); + d_byte_offset += d_nbits; + } + else { + d_nresid = d_nbits-(8-d_byte_offset); + int mask = ((1<<(8-d_byte_offset))-1); + d_partial_byte |= (bits & mask) << d_byte_offset; + d_resid = bits >> (8-d_byte_offset); + d_byte_offset += (d_nbits - d_nresid); + } + //printf("demod symbol: %.4f + j%.4f bits: %x partial_byte: %x byte_offset: %d resid: %x nresid: %d\n", + // in[i-1].real(), in[i-1].imag(), bits, d_partial_byte, d_byte_offset, d_resid, d_nresid); + } + + if(d_byte_offset == 8) { + //printf("demod byte: %x \n\n", d_partial_byte); + out[bytes_produced++] = d_partial_byte; + d_byte_offset = 0; + d_partial_byte = 0; + } + } + //std::cerr << "accum_error " << accum_error << std::endl; + + float angle = arg(accum_error); + + d_freq = d_freq - d_freq_gain*angle; + d_phase = d_phase + d_freq - d_phase_gain*angle; + if (d_phase >= 2*M_PI) d_phase -= 2*M_PI; + if (d_phase <0) d_phase += 2*M_PI; + + //if(VERBOSE) + // std::cerr << angle << "\t" << d_freq << "\t" << d_phase << "\t" << std::endl; + + return bytes_produced; +} + + +digital_ofdm_frame_sink_sptr +digital_make_ofdm_frame_sink(const std::vector<gr_complex> &sym_position, + const std::vector<unsigned char> &sym_value_out, + gr_msg_queue_sptr target_queue, unsigned int occupied_carriers, + float phase_gain, float freq_gain) +{ + return gnuradio::get_initial_sptr(new digital_ofdm_frame_sink(sym_position, sym_value_out, + target_queue, occupied_carriers, + phase_gain, freq_gain)); +} + + +digital_ofdm_frame_sink::digital_ofdm_frame_sink(const std::vector<gr_complex> &sym_position, + const std::vector<unsigned char> &sym_value_out, + gr_msg_queue_sptr target_queue, unsigned int occupied_carriers, + float phase_gain, float freq_gain) + : gr_sync_block ("ofdm_frame_sink", + gr_make_io_signature2 (2, 2, sizeof(gr_complex)*occupied_carriers, sizeof(char)), + gr_make_io_signature (1, 1, sizeof(gr_complex)*occupied_carriers)), + d_target_queue(target_queue), d_occupied_carriers(occupied_carriers), + d_byte_offset(0), d_partial_byte(0), + d_resid(0), d_nresid(0),d_phase(0),d_freq(0),d_phase_gain(phase_gain),d_freq_gain(freq_gain), + d_eq_gain(0.05) +{ + std::string carriers = "FE7F"; + + // A bit hacky to fill out carriers to occupied_carriers length + int diff = (d_occupied_carriers - 4*carriers.length()); + while(diff > 7) { + carriers.insert(0, "f"); + carriers.insert(carriers.length(), "f"); + diff -= 8; + } + + // if there's extras left to be processed + // divide remaining to put on either side of current map + // all of this is done to stick with the concept of a carrier map string that + // can be later passed by the user, even though it'd be cleaner to just do this + // on the carrier map itself + int diff_left=0; + int diff_right=0; + + // dictionary to convert from integers to ascii hex representation + char abc[16] = {'0', '1', '2', '3', '4', '5', '6', '7', + '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; + if(diff > 0) { + char c[2] = {0,0}; + + diff_left = (int)ceil((float)diff/2.0f); // number of carriers to put on the left side + c[0] = abc[(1 << diff_left) - 1]; // convert to bits and move to ASCI integer + carriers.insert(0, c); + + diff_right = diff - diff_left; // number of carriers to put on the right side + c[0] = abc[0xF^((1 << diff_right) - 1)]; // convert to bits and move to ASCI integer + carriers.insert(carriers.length(), c); + } + + // It seemed like such a good idea at the time... + // because we are only dealing with the occupied_carriers + // at this point, the diff_left in the following compensates + // for any offset from the 0th carrier introduced + unsigned int i,j,k; + for(i = 0; i < (d_occupied_carriers/4)+diff_left; i++) { + char c = carriers[i]; + for(j = 0; j < 4; j++) { + k = (strtol(&c, NULL, 16) >> (3-j)) & 0x1; + if(k) { + d_subcarrier_map.push_back(4*i + j - diff_left); + } + } + } + + // make sure we stay in the limit currently imposed by the occupied_carriers + if(d_subcarrier_map.size() > d_occupied_carriers) { + throw std::invalid_argument("digital_ofdm_mapper_bcv: subcarriers allocated exceeds size of occupied carriers"); + } + + d_bytes_out = new unsigned char[d_occupied_carriers]; + d_dfe.resize(occupied_carriers); + fill(d_dfe.begin(), d_dfe.end(), gr_complex(1.0,0.0)); + + set_sym_value_out(sym_position, sym_value_out); + + enter_search(); +} + +digital_ofdm_frame_sink::~digital_ofdm_frame_sink () +{ + delete [] d_bytes_out; +} + +bool +digital_ofdm_frame_sink::set_sym_value_out(const std::vector<gr_complex> &sym_position, + const std::vector<unsigned char> &sym_value_out) +{ + if (sym_position.size() != sym_value_out.size()) + return false; + + if (sym_position.size()<1) + return false; + + d_sym_position = sym_position; + d_sym_value_out = sym_value_out; + d_nbits = (unsigned long)ceil(log10(float(d_sym_value_out.size())) / log10(2.0)); + + return true; +} + + +int +digital_ofdm_frame_sink::work (int noutput_items, + gr_vector_const_void_star &input_items, + gr_vector_void_star &output_items) +{ + const gr_complex *in = (const gr_complex *) input_items[0]; + const char *sig = (const char *) input_items[1]; + unsigned int j = 0; + unsigned int bytes=0; + + // If the output is connected, send it the derotated symbols + if(output_items.size() >= 1) + d_derotated_output = (gr_complex *)output_items[0]; + else + d_derotated_output = NULL; + + if (VERBOSE) + fprintf(stderr,">>> Entering state machine\n"); + + switch(d_state) { + + case STATE_SYNC_SEARCH: // Look for flag indicating beginning of pkt + if (VERBOSE) + fprintf(stderr,"SYNC Search, noutput=%d\n", noutput_items); + + if (sig[0]) { // Found it, set up for header decode + enter_have_sync(); + } + break; + + case STATE_HAVE_SYNC: + // only demod after getting the preamble signal; otherwise, the + // equalizer taps will screw with the PLL performance + bytes = demapper(&in[0], d_bytes_out); + + if (VERBOSE) { + if(sig[0]) + printf("ERROR -- Found SYNC in HAVE_SYNC\n"); + fprintf(stderr,"Header Search bitcnt=%d, header=0x%08x\n", + d_headerbytelen_cnt, d_header); + } + + j = 0; + while(j < bytes) { + d_header = (d_header << 8) | (d_bytes_out[j] & 0xFF); + j++; + + if (++d_headerbytelen_cnt == HEADERBYTELEN) { + + 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()){ + enter_have_header(); + + if (VERBOSE) + printf("\nPacket Length: %d\n", d_packetlen); + + while((j < bytes) && (d_packetlen_cnt < d_packetlen)) { + d_packet[d_packetlen_cnt++] = d_bytes_out[j++]; + } + + if(d_packetlen_cnt == d_packetlen) { + gr_message_sptr msg = + gr_make_message(0, d_packet_whitener_offset, 0, d_packetlen); + memcpy(msg->msg(), d_packet, d_packetlen_cnt); + d_target_queue->insert_tail(msg); // send it + msg.reset(); // free it up + + enter_search(); + } + } + else { + enter_search(); // bad header + } + } + } + break; + + case STATE_HAVE_HEADER: + bytes = demapper(&in[0], d_bytes_out); + + if (VERBOSE) { + if(sig[0]) + printf("ERROR -- Found SYNC in HAVE_HEADER at %d, length of %d\n", d_packetlen_cnt, d_packetlen); + fprintf(stderr,"Packet Build\n"); + } + + j = 0; + while(j < bytes) { + d_packet[d_packetlen_cnt++] = d_bytes_out[j++]; + + if (d_packetlen_cnt == d_packetlen){ // packet is filled + // build a message + // NOTE: passing header field as arg1 is not scalable + gr_message_sptr msg = + gr_make_message(0, d_packet_whitener_offset, 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 + + return 1; +} |