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+/* -*- c++ -*- */
+/*
+ * Copyright 2006-2008,2010,2011 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_mapper_bcv.h>
+#include <gr_io_signature.h>
+#include <stdexcept>
+#include <string.h>
+
+digital_ofdm_mapper_bcv_sptr
+digital_make_ofdm_mapper_bcv (const std::vector<gr_complex> &constellation, unsigned int msgq_limit,
+ unsigned int occupied_carriers, unsigned int fft_length)
+{
+ return gnuradio::get_initial_sptr(new digital_ofdm_mapper_bcv (constellation, msgq_limit,
+ occupied_carriers, fft_length));
+}
+
+// Consumes 1 packet and produces as many OFDM symbols of fft_length to hold the full packet
+digital_ofdm_mapper_bcv::digital_ofdm_mapper_bcv (const std::vector<gr_complex> &constellation, unsigned int msgq_limit,
+ unsigned int occupied_carriers, unsigned int fft_length)
+ : gr_sync_block ("ofdm_mapper_bcv",
+ gr_make_io_signature (0, 0, 0),
+ gr_make_io_signature2 (1, 2, sizeof(gr_complex)*fft_length, sizeof(char))),
+ d_constellation(constellation),
+ d_msgq(gr_make_msg_queue(msgq_limit)), d_msg_offset(0), d_eof(false),
+ d_occupied_carriers(occupied_carriers),
+ d_fft_length(fft_length),
+ d_bit_offset(0),
+ d_pending_flag(0),
+ d_resid(0),
+ d_nresid(0)
+{
+ if (!(d_occupied_carriers <= d_fft_length))
+ throw std::invalid_argument("digital_ofdm_mapper_bcv: occupied carriers must be <= fft_length");
+
+ // this is not the final form of this solution since we still use the occupied_tones concept,
+ // which would get us into trouble if the number of carriers we seek is greater than the occupied carriers.
+ // Eventually, we will get rid of the occupied_carriers concept.
+ 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);
+ }
+
+ // find out how many zeros to pad on the sides; the difference between the fft length and the subcarrier
+ // mapping size in chunks of four. This is the number to pack on the left and this number plus any
+ // residual nulls (if odd) will be packed on the right.
+ diff = (d_fft_length/4 - carriers.length())/2;
+
+ unsigned int i,j,k;
+ for(i = 0; i < carriers.length(); i++) {
+ char c = carriers[i]; // get the current hex character from the string
+ for(j = 0; j < 4; j++) { // walk through all four bits
+ k = (strtol(&c, NULL, 16) >> (3-j)) & 0x1; // convert to int and extract next bit
+ if(k) { // if bit is a 1,
+ d_subcarrier_map.push_back(4*(i+diff) + j); // use this subcarrier
+ }
+ }
+ }
+
+ // 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_nbits = (unsigned long)ceil(log10(float(d_constellation.size())) / log10(2.0));
+}
+
+digital_ofdm_mapper_bcv::~digital_ofdm_mapper_bcv(void)
+{
+}
+
+int digital_ofdm_mapper_bcv::randsym()
+{
+ return (rand() % d_constellation.size());
+}
+
+int
+digital_ofdm_mapper_bcv::work(int noutput_items,
+ gr_vector_const_void_star &input_items,
+ gr_vector_void_star &output_items)
+{
+ gr_complex *out = (gr_complex *)output_items[0];
+
+ unsigned int i=0;
+
+ //printf("OFDM BPSK Mapper: ninput_items: %d noutput_items: %d\n", ninput_items[0], noutput_items);
+
+ if(d_eof) {
+ return -1;
+ }
+
+ if(!d_msg) {
+ d_msg = d_msgq->delete_head(); // block, waiting for a message
+ d_msg_offset = 0;
+ d_bit_offset = 0;
+ d_pending_flag = 1; // new packet, write start of packet flag
+
+ if((d_msg->length() == 0) && (d_msg->type() == 1)) {
+ d_msg.reset();
+ return -1; // We're done; no more messages coming.
+ }
+ }
+
+ char *out_flag = 0;
+ if(output_items.size() == 2)
+ out_flag = (char *) output_items[1];
+
+
+ // Build a single symbol:
+ // Initialize all bins to 0 to set unused carriers
+ memset(out, 0, d_fft_length*sizeof(gr_complex));
+
+ i = 0;
+ unsigned char bits = 0;
+ //while((d_msg_offset < d_msg->length()) && (i < d_occupied_carriers)) {
+ while((d_msg_offset < d_msg->length()) && (i < d_subcarrier_map.size())) {
+
+ // need new data to process
+ if(d_bit_offset == 0) {
+ d_msgbytes = d_msg->msg()[d_msg_offset];
+ //printf("mod message byte: %x\n", d_msgbytes);
+ }
+
+ if(d_nresid > 0) {
+ // take the residual bits, fill out nbits with info from the new byte, and put them in the symbol
+ d_resid |= (((1 << d_nresid)-1) & d_msgbytes) << (d_nbits - d_nresid);
+ bits = d_resid;
+
+ out[d_subcarrier_map[i]] = d_constellation[bits];
+ i++;
+
+ d_bit_offset += d_nresid;
+ d_nresid = 0;
+ d_resid = 0;
+ //printf("mod bit(r): %x resid: %x nresid: %d bit_offset: %d\n",
+ // bits, d_resid, d_nresid, d_bit_offset);
+ }
+ else {
+ if((8 - d_bit_offset) >= d_nbits) { // test to make sure we can fit nbits
+ // take the nbits number of bits at a time from the byte to add to the symbol
+ bits = ((1 << d_nbits)-1) & (d_msgbytes >> d_bit_offset);
+ d_bit_offset += d_nbits;
+
+ out[d_subcarrier_map[i]] = d_constellation[bits];
+ i++;
+ }
+ else { // if we can't fit nbits, store them for the next
+ // saves d_nresid bits of this message where d_nresid < d_nbits
+ unsigned int extra = 8-d_bit_offset;
+ d_resid = ((1 << extra)-1) & (d_msgbytes >> d_bit_offset);
+ d_bit_offset += extra;
+ d_nresid = d_nbits - extra;
+ }
+
+ }
+
+ if(d_bit_offset == 8) {
+ d_bit_offset = 0;
+ d_msg_offset++;
+ }
+ }
+
+ // Ran out of data to put in symbol
+ if (d_msg_offset == d_msg->length()) {
+ if(d_nresid > 0) {
+ d_resid |= 0x00;
+ bits = d_resid;
+ d_nresid = 0;
+ d_resid = 0;
+ }
+
+ //while(i < d_occupied_carriers) { // finish filling out the symbol
+ while(i < d_subcarrier_map.size()) { // finish filling out the symbol
+ out[d_subcarrier_map[i]] = d_constellation[randsym()];
+
+ i++;
+ }
+
+ if (d_msg->type() == 1) // type == 1 sets EOF
+ d_eof = true;
+ d_msg.reset(); // finished packet, free message
+ assert(d_bit_offset == 0);
+ }
+
+ if (out_flag)
+ out_flag[0] = d_pending_flag;
+ d_pending_flag = 0;
+
+ return 1; // produced symbol
+}