/* -*- c++ -*- */
/*
 * Copyright 2007 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 <cvsd_encode_sb.h>
#include <gr_io_signature.h>
#include <limits.h>

/*
 * Create a new instance of cvsd_encode_sb and return
 * a boost shared_ptr.  This is effectively the public constructor.
 */
cvsd_encode_sb_sptr 
cvsd_make_encode_sb (short min_step, short max_step, double step_decay,
		     double accum_decay,  int K, int J,
		     short pos_accum_max, short neg_accum_max)
{
  return cvsd_encode_sb_sptr (new cvsd_encode_sb (min_step, max_step,
						  step_decay, accum_decay, K, J,
						  pos_accum_max, neg_accum_max));
}

cvsd_encode_sb::cvsd_encode_sb (short min_step, short max_step, double step_decay, 
				double accum_decay, int K, int J,
				short pos_accum_max, short neg_accum_max)
  : gr_sync_decimator ("cvsd_encode_sb",
		       gr_make_io_signature (1, 1, sizeof (short)),
		       gr_make_io_signature (1, 1, sizeof (unsigned char)),
		       8),
    d_min_step (min_step), d_max_step(max_step), d_step_decay(step_decay),
    d_accum_decay(accum_decay), d_K(K), d_J(J), 
    d_pos_accum_max(pos_accum_max), d_neg_accum_max(neg_accum_max),
    d_accum(0), 
    d_loop_counter(1), 
    d_runner(0),
    d_stepsize(min_step)

{
  assert(d_pos_accum_max <= SHRT_MAX);
  assert(d_neg_accum_max >= -SHRT_MAX);
  assert(d_K <= 32);
  assert(d_J <= d_K);

  // nothing else required in this example
}


cvsd_encode_sb::~cvsd_encode_sb ()
{
  // nothing else required in this example
}

unsigned char cvsd_encode_sb::cvsd_bitwise_sum (unsigned int input)
{
  unsigned int temp=input;
  unsigned char bits=0;
  
  while(temp) {
    temp=temp&(temp-1);
    bits++;
  }
  return bits;
}

int cvsd_encode_sb::cvsd_round (double input)
{
  double temp;
  temp=input+0.5;
  temp=floor(temp);
  
  return (int)temp;
}

unsigned int cvsd_encode_sb::cvsd_pow (short radix, short power)
{
  double d_radix = (double) radix;
  int i_power = (int) power;
  double output;

  output=pow(d_radix,i_power);
  return ( (unsigned int) cvsd_round(output));  
}



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

  unsigned short i=0;		 // 2 bytes, 0 .. 65,535
  unsigned char output_bit=0;	 // 1 byte, 0 .. 255
  unsigned char output_byte=0;	 // 1 bytes 0.255
  unsigned char bit_count=0;		 // 1 byte, 0 .. 255
  unsigned int mask=0;		 // 4 bytes, 0 .. 4,294,967,295
  
  // Loop through each input data point
  for(i = 0; i < noutput_items*8; i++) {
    if((int)in[i] >= d_accum) {    // Note:  sign((data(n)-accum))
      output_bit=1;
    }
    else {
      output_bit=0;
    }
    
    // Update Accum (i.e. the reference value)
    if (output_bit) {
      d_accum=d_accum+d_stepsize;
      //printf("Addding %d to the accum; the result is: %d.\n", d_stepsize, d_accum);
    }
    else {
      d_accum=d_accum-d_stepsize;
      //printf("Subtracting %d to the accum; the result is: %d.\n", d_stepsize, d_accum);
    }

    // Multiply by Accum_Decay
    d_accum=(cvsd_round(d_accum*d_accum_decay));

    // Check for overflow
    if (d_accum >= ((int)d_pos_accum_max)) {
      d_accum = (int)d_pos_accum_max;
    }
    else if(d_accum <= ((int) d_neg_accum_max)) {
      d_accum = (int) d_neg_accum_max;
    }
		 
    // Update runner with the last output bit
    // Update Step Size
    if (d_loop_counter >= d_J) { // Run this only if you have >= J bits in your shift register
      mask=(cvsd_pow(2, d_J) - 1);
      if ((cvsd_bitwise_sum(d_runner & mask) >= d_J) || (cvsd_bitwise_sum((~d_runner) & mask) >= d_J)) {
	// Runs of 1s and 0s
	d_stepsize = std::min( (short)(d_stepsize + d_min_step), d_max_step);
      }
      else {
	// No runs of 1s and 0s
	d_stepsize = std::max( (short)cvsd_round(d_stepsize*d_step_decay), d_min_step);     
      }
    }
	     
    // Runner is a shift-register; shift left, add on newest output bit
    d_runner = (d_runner<<1) | ((unsigned int) output_bit);

    // Update the ouput type; shift left, add on newest output bit
    // If you have put in 8 bits, output it as a byte
    output_byte = (output_byte<<1) | output_bit;
    bit_count++;
    
    if (d_loop_counter <= d_K) {
      d_loop_counter++;
    }

    // If you have put 8 bits, output and clear.
    if (bit_count==8) {
      // Read in short from the file
      *(out++) = output_byte;
      
      // Reset the bit_count
      bit_count=0;
      output_byte=0;
    }
  } // While

  return noutput_items;
}