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   1 /* -*- c++ -*- */
   2 /*
   3  * Copyright 2007 Free Software Foundation, Inc.
   4  *
   5  * This file is part of GNU Radio
   6  *
   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 2, or (at your option)
  10  * any later version.
  11  *
  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.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, write to the Free Software Foundation, Inc.,
  19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <gr_ofdm_insert_preamble.h>
  27 #include <gr_io_signature.h>
  28 #include <stdexcept>
  29 #include <iostream>
  30
  31 gr_ofdm_insert_preamble_sptr
  32 gr_make_ofdm_insert_preamble(int fft_length,
  33                              const std::vector<std::vector<gr_complex> > &preamble)
  34 {
  35   return gr_ofdm_insert_preamble_sptr(new gr_ofdm_insert_preamble(fft_length,
  36                                                                   preamble));
  37 }
  38
  39 gr_ofdm_insert_preamble::gr_ofdm_insert_preamble
  40        (int fft_length,
  41         const std::vector<std::vector<gr_complex> > &preamble)
  42   : gr_block("ofdm_insert_preamble",
  43              gr_make_io_signature2(2, 2,
  44                                    sizeof(gr_complex)*fft_length,
  45                                    sizeof(char)),
  46              gr_make_io_signature2(1, 2,
  47                                    sizeof(gr_complex)*fft_length,
  48                                    sizeof(char))),
  49     d_fft_length(fft_length),
  50     d_preamble(preamble),
  51     d_state(ST_IDLE),
  52     d_nsymbols_output(0),
  53     d_pending_flag(0)
  54 {
  55   // sanity check preamble symbols
  56   for (size_t i = 0; i < d_preamble.size(); i++){
  57     if (d_preamble[i].size() != (size_t) d_fft_length)
  58       throw std::invalid_argument("gr_ofdm_insert_preamble: invalid length for preamble symbol");
  59   }
  60
  61   enter_idle();
  62 }
  63
  64
  65 gr_ofdm_insert_preamble::~gr_ofdm_insert_preamble()
  66 {
  67 }
  68
  69 int
  70 gr_ofdm_insert_preamble::general_work (int noutput_items,
  71                                        gr_vector_int &ninput_items_v,
  72                                        gr_vector_const_void_star &input_items,
  73                                        gr_vector_void_star &output_items)
  74 {
  75   int ninput_items = std::min(ninput_items_v[0], ninput_items_v[1]);
  76   const gr_complex *in_sym = (const gr_complex *) input_items[0];
  77   const unsigned char *in_flag = (const unsigned char *) input_items[1];
  78
  79   gr_complex *out_sym = (gr_complex *) output_items[0];
  80   unsigned char *out_flag = 0;
  81   if (output_items.size() == 2)
  82     out_flag = (unsigned char *) output_items[1];
  83
  84
  85   int no = 0;   // number items output
  86   int ni = 0;   // number items read from input
  87
  88
  89 #define write_out_flag()                        \
  90   do { if (out_flag)                            \
  91           out_flag[no] = d_pending_flag;        \
  92        d_pending_flag = 0;                      \
  93   } while(0)
  94
  95
  96   while (no < noutput_items && ni < ninput_items){
  97     switch(d_state){
  98     case ST_IDLE:
  99       if (in_flag[ni] & 0x1)    // this is first symbol of new payload
 100         enter_preamble();
 101       else
 102         ni++;                   // eat one input symbol
 103       break;
 104
 105     case ST_PREAMBLE:
 106       assert(in_flag[ni] & 0x1);
 107       if (d_nsymbols_output >= (int) d_preamble.size()){
 108         // we've output all the preamble
 109         enter_first_payload();
 110       }
 111       else {
 112         memcpy(&out_sym[no * d_fft_length],
 113                &d_preamble[d_nsymbols_output][0],
 114                d_fft_length*sizeof(gr_complex));
 115
 116         write_out_flag();
 117         no++;
 118         d_nsymbols_output++;
 119       }
 120       break;
 121
 122     case ST_FIRST_PAYLOAD:
 123       // copy first payload symbol from input to output
 124       memcpy(&out_sym[no * d_fft_length],
 125              &in_sym[ni * d_fft_length],
 126              d_fft_length * sizeof(gr_complex));
 127
 128       write_out_flag();
 129       no++;
 130       ni++;
 131       enter_payload();
 132       break;
 133
 134     case ST_PAYLOAD:
 135       if (in_flag[ni] & 0x1){   // this is first symbol of a new payload
 136         enter_preamble();
 137         break;
 138       }
 139
 140       // copy a symbol from input to output
 141       memcpy(&out_sym[no * d_fft_length],
 142              &in_sym[ni * d_fft_length],
 143              d_fft_length * sizeof(gr_complex));
 144
 145       write_out_flag();
 146       no++;
 147       ni++;
 148       break;
 149
 150     default:
 151       std::cerr << "gr_ofdm_insert_preamble: (can't happen) invalid state, resetting\n";
 152       enter_idle();
 153     }
 154   }
 155
 156   consume_each(ni);
 157   return no;
 158 }
 159
 160 void
 161 gr_ofdm_insert_preamble::enter_idle()
 162 {
 163   d_state = ST_IDLE;
 164   d_nsymbols_output = 0;
 165   d_pending_flag = 0;
 166 }
 167
 168 void
 169 gr_ofdm_insert_preamble::enter_preamble()
 170 {
 171   d_state = ST_PREAMBLE;
 172   d_nsymbols_output = 0;
 173   d_pending_flag = 1;
 174 }
 175
 176 void
 177 gr_ofdm_insert_preamble::enter_first_payload()
 178 {
 179   d_state = ST_FIRST_PAYLOAD;
 180 }
 181
 182 void
 183 gr_ofdm_insert_preamble::enter_payload()
 184 {
 185   d_state = ST_PAYLOAD;
 186 }