/* -*- 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 2, 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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, 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 <ofdm_tx_cc.h>
#include <gr_io_signature.h>

#include <gri_fft.h>
#include <math.h>

/*
 * Create a new instance of gr_ofdm_tx_cc and return
 * a boost shared_ptr.  This is effectively the public constructor.
 */
ofdm_tx_cc_sptr 
ofdm_do_tx_cc (int ofdm_sym_len, int gi_len, int fft_len)
{
  return ofdm_tx_cc_sptr (new ofdm_tx_cc (ofdm_sym_len, gi_len, fft_len));
}

/*
 * 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
 * Takes length of OFDM symbol (including guard interval) and guard interval length as 
 * arguments. Variable FFT length and subcarrier selection mask is implemented later.
 */
ofdm_tx_cc::ofdm_tx_cc (int ofdm_sym_len, int gi_len, int fft_len)
  : gr_block ("ofdm_tx_vcc",
		   gr_make_io_signature (MIN_IN, MAX_IN, (ofdm_sym_len-gi_len)*sizeof(gr_complex)),
		   gr_make_io_signature (MIN_OUT, MAX_OUT, ofdm_sym_len * sizeof(gr_complex)))
{
	d_ofdm_sym_len = ofdm_sym_len;
	d_gi_len = gi_len;
	d_fft_len = ofdm_sym_len-gi_len; // FIXME: not yet implemented

	// OFDM symbols can't be split, contrain request size
	set_output_multiple(d_ofdm_sym_len);

	// set approximate out rate 
	set_relative_rate((double)(d_ofdm_sym_len) / (double)(d_ofdm_sym_len-d_gi_len));

	d_fft = new gri_fft_complex(d_fft_len, true);
}

/*
 * Our virtual destructor.
 */
ofdm_tx_cc::~ofdm_tx_cc ()
{
	delete d_fft;
}

/*
 * Implementation of gr_block::forecast() - estimate the number of input samples, if we are asked to
 * output noutput_items samples.
 */
void
ofdm_tx_cc::forecast (int noutput_items, gr_vector_int &ninput_items_required) 
{
	// noutput_items should be a multiple of d_ofdm_sym_len (see constructor)
	assert ((noutput_items % d_ofdm_sym_len) == 0);

	int nblocks = noutput_items / d_ofdm_sym_len;
	int input_required = nblocks * (d_ofdm_sym_len-d_gi_len);

	unsigned ninputs = ninput_items_required.size();
	for (unsigned int i = 0; i < ninputs; i++)
		ninput_items_required[i] = input_required;
}


/*
 * Here the actual work is done - "d_ofdm_sym_len-d_gi_len" complex samples are consumed and
 * "d_ofdm_sym_len" samples are written.
 */

int 
ofdm_tx_cc::general_work (int noutput_items, 
			  gr_vector_int &ninput_items,
			  gr_vector_const_void_star &input_items,
			  gr_vector_void_star &output_items)
{
  // pointers to data
  const gr_complex *in = (const gr_complex *) input_items[0];
  gr_complex *out = (gr_complex *) output_items[0];

  int out_count=0; // counts the number of written complex samples
  int in_count=0; // counts number of samples consumed

  printf("available in (samples): %i\n", ninput_items[0]);
  printf("requested out (samples): %i\n", noutput_items);

  while(out_count<noutput_items) 
  {
  	memcpy(d_fft->get_inbuf(), in, d_fft_len*sizeof(gr_complex)); // copy to input buffer
  	d_fft->execute(); // compute fft
  	// cyclic prefix is repetition of the end in the beginning
  	memcpy(out, d_fft->get_outbuf()+(d_fft_len-d_gi_len), d_gi_len*sizeof(gr_complex)); // guard interval; last argument of memcpy is length in bytes
  	memcpy(out+d_gi_len, d_fft->get_outbuf(), d_fft_len*sizeof(gr_complex)); // copy data 
	
	// increase pointers, counters
  	in += d_ofdm_sym_len-d_gi_len;
  	out += d_ofdm_sym_len;
	out_count += d_ofdm_sym_len;
	in_count += d_ofdm_sym_len-d_gi_len;
  }

  // noutput_items should always be a multiple of d_ofdm_sym_len, so the assert shouldn't fail now
  assert (out_count == noutput_items);

  // Tell runtime system how many input items we consumed.
  consume_each(in_count);

  // Tell runtime system how many output items we produced.
  return out_count;
}