/* -*- c++ -*- */
/*
 * Copyright 2004 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.
 */

/*
 * config.h is generated by configure.  It contains the results
 * of probing for features, options etc.  It should be the first
 * file included in your .cc file.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <pn_correlator_cc.h>
#include <gr_io_signature.h>

/*
 * Create a new instance of pn_correlator_cc and return
 * a boost shared_ptr.  This is effectively the public constructor.
 */
pn_correlator_cc_sptr 
pn_make_correlator_cc (int degree, int mask, int seed)
{
  return pn_correlator_cc_sptr (new pn_correlator_cc (degree, mask, seed));
}

/*
 * Specify constraints on number of input and output streams.
 * This info is used to construct the input and output signatures
 * (2nd & 3rd args to gr_block's constructor).  The input and
 * output signatures are used by the runtime system to
 * check that a valid number and type of inputs and outputs
 * are connected to this block.  In this case, we accept
 * only 1 input and 1 output.
 */
static const int MIN_IN = 1;	// mininum number of input streams
static const int MAX_IN = 1;	// maximum number of input streams
static const int MIN_OUT = 1;	// minimum number of output streams
static const int MAX_OUT = 1;	// maximum number of output streams

/*
 * The private constructor
 */
pn_correlator_cc::pn_correlator_cc (int degree, int mask, int seed)
  : gr_block("correlator_cc",
	               gr_make_io_signature (MIN_IN, MAX_IN, sizeof (float)),
	               gr_make_io_signature (MIN_OUT, MAX_OUT, sizeof (float)))
                       //(unsigned int)((1ULL << degree)-1)) // PN code length
{
  d_len = (unsigned int)((1ULL << degree)-1);
  if (mask == 0)
    mask = gri_glfsr::glfsr_mask(degree);
  d_reference = new gri_glfsr(mask, seed);
  for (int i = 0; i < d_len; i++)	// initialize to last value in sequence
    d_pn = 2.0*d_reference->next_bit()-1.0;
}


void
pn_correlator_cc::forecast (int noutput_items, gr_vector_int &ninput_items_required)
{
  int input_required =   noutput_items ;
  unsigned ninputs = ninput_items_required.size();
  for (unsigned int i = 0; i < ninputs; i++) {
    ninput_items_required[i] = input_required;
  }
}


/*
 * Our virtual destructor.
 */
pn_correlator_cc::~pn_correlator_cc ()
{
  delete d_reference;
}



int 
pn_correlator_cc::general_work (int noutput_items,
                               gr_vector_int &ninput_items,
			       gr_vector_const_void_star &input_items,
			       gr_vector_void_star &output_items)
{
  const float *in = (const float *) input_items[0];
  float *out = (float *) output_items[0];
  
  float sum;
  int i=0;

 
  while(abs(sum)<0.8)
 {
    sum =0;
    for (int j = 0; j < d_len; j++) {
      if (j != 0)		            // retard PN generator one sample per period
	d_pn = 2.0*d_reference->next_bit()-1.0; // no conditionals
      sum+= (2*(*in++)-1) * d_pn;
    }
    sum = sum/d_len;
  

  }
  for(int i=0;i<noutput_items;i++)
{
  d_pn = d_reference->next_bit();
  if(d_pn == *in++)
     *out++=0;
  else
     *out++=1;
 }
  consume_each (noutput_items);
  return noutput_items;
}