check_lfsr_32k_s_impl.cc

/* -*- c++ -*- */
/*
 * Copyright 2004,2010,2013 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 "check_lfsr_32k_s_impl.h"
#include <gnuradio/io_signature.h>
#include <stdlib.h>
#include <stdio.h>

namespace gr {
  namespace blocks {

    check_lfsr_32k_s::sptr
    check_lfsr_32k_s::make()
    {
      return gnuradio::get_initial_sptr
        (new check_lfsr_32k_s_impl());
    }

    check_lfsr_32k_s_impl::check_lfsr_32k_s_impl()
      : sync_block("check_lfsr_32k",
                       io_signature::make(1, 1, sizeof(short)),
                      io_signature::make(0, 0, 0)),
        d_state(SEARCHING), d_history(0), d_ntotal(0), d_nright(0),
        d_runlength(0), d_index(0)
    {
      lfsr_32k lfsr;

      for(int i = 0; i < BUFSIZE; i++)
        d_buffer[i] = lfsr.next_short();

      enter_SEARCHING();
    }

    check_lfsr_32k_s_impl::~check_lfsr_32k_s_impl()
    {
    }

    int
    check_lfsr_32k_s_impl::work(int noutput_items,
                                gr_vector_const_void_star &input_items,
                                gr_vector_void_star &output_items)
    {
      unsigned short *in = (unsigned short*)input_items[0];

      for(int i = 0; i < noutput_items; i++) {
        unsigned short x = in[i];
        unsigned short expected;

        switch(d_state) {
        case MATCH0:
          if(x == d_buffer[0])
            enter_MATCH1();
          break;

        case MATCH1:
          if(x == d_buffer[1])
            enter_MATCH2();
          else
            enter_MATCH0();
          break;

        case MATCH2:
          if(x == d_buffer[2])
            enter_LOCKED();
          else
            enter_MATCH0();
          break;

        case LOCKED:
          expected = d_buffer[d_index];
          d_index = d_index + 1;
          if(d_index >= BUFSIZE)
            d_index = 0;

          if(x == expected)
            right();
          else {
            wrong();
            log_error(expected, x);
            if(wrong_three_times())
              enter_SEARCHING();
          }
          break;

        default:
          abort();
        }

        d_ntotal++;
      }

      return noutput_items;
    }

    void
    check_lfsr_32k_s_impl::enter_SEARCHING()
    {
      d_state = SEARCHING;
      wrong();  // reset history
      wrong();
      wrong();

      d_runlength = 0;
      d_index = 0;      // reset LFSR to beginning

      if(0)
        fprintf(stdout, "check_lfsr_32k: enter_SEARCHING at offset %8ld (0x%08lx)\n",
                d_ntotal, d_ntotal);

      enter_MATCH0();
    }

    void
    check_lfsr_32k_s_impl::enter_MATCH0()
    {
      d_state = MATCH0;
    }

    void
    check_lfsr_32k_s_impl::enter_MATCH1()
    {
      d_state = MATCH1;
    }

    void
    check_lfsr_32k_s_impl::enter_MATCH2()
    {
      d_state = MATCH2;
    }

    void
    check_lfsr_32k_s_impl::enter_LOCKED()
    {
      d_state = LOCKED;
      right();          // setup history
      right();
      right();

      d_index = 3;      // already matched first 3 items

      if(0)
        fprintf(stdout, "check_lfsr_32k: enter_LOCKED at offset %8ld (0x%08lx)\n",
                d_ntotal, d_ntotal);
    }

    void
    check_lfsr_32k_s_impl::log_error(unsigned short expected, unsigned short actual)
    {
      if(0)
        fprintf(stdout,
                "check_lfsr_32k: expected %5d (0x%04x) got %5d (0x%04x) offset %8ld (0x%08lx)\n",
                expected, expected, actual, actual, d_ntotal, d_ntotal);
    }

  } /* namespace blocks */
} /* namespace gr */