/* -*- c++ -*- */
/*
 * Copyright 2012,2014 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 "stream_mux_impl.h"
#include <gnuradio/io_signature.h>
#include <boost/foreach.hpp>
#include <cstring>

namespace gr {
  namespace blocks {

    stream_mux::sptr stream_mux::make(size_t itemsize, const std::vector<int> &lengths)
    {
      return gnuradio::get_initial_sptr(new stream_mux_impl(itemsize, lengths));
    }

    stream_mux_impl::stream_mux_impl(size_t itemsize, const std::vector<int> &lengths)
      : block("stream_mux",
		 io_signature::make (1, -1, itemsize),
		 io_signature::make (1, 1, itemsize)),
	d_itemsize(itemsize),
	d_stream(0),
	d_residual(0),
	d_lengths(lengths)
    {
      while (d_lengths[d_stream] == 0) {
        d_stream++;
        if (d_stream == d_lengths.size()) {
          throw std::invalid_argument("At least one size must be non-zero.");
        }
      }
      d_residual = d_lengths[d_stream];
    }

    void
    stream_mux_impl::forecast(int noutput_items, gr_vector_int &ninput_items_required)
    {
      unsigned ninputs = ninput_items_required.size ();
      for (unsigned i = 0; i < ninputs; i++) {
	// Only active inputs *need* items, for the rest, it would just be nice
	ninput_items_required[i] = (d_stream == i ? 1 : 0);
      }
    }


    int
    stream_mux_impl::general_work(int noutput_items,
          gr_vector_int &ninput_items,
          gr_vector_const_void_star &input_items,
          gr_vector_void_star &output_items
    ){
      char *out = (char *) output_items[0];
      const char *in;
      int out_index = 0; // Items written
      gr_vector_int input_index(d_lengths.size(), 0); // Items read

      while (out_index < noutput_items) {
        if (ninput_items[d_stream] <= input_index[d_stream]) {
          break;
        }
        int space_left_in_buffers = std::min(
              noutput_items - out_index, // Space left in output buffer
              ninput_items[d_stream] - input_index[d_stream] // Space left in input buffer
        );
        int items_to_copy = std::min(
            space_left_in_buffers,
            d_residual
        );
        in = (const char *) input_items[d_stream] + input_index[d_stream]*d_itemsize;
        memcpy(&out[out_index*d_itemsize], in, items_to_copy*d_itemsize);
        out_index += items_to_copy;
        input_index[d_stream] += items_to_copy;
        d_residual -= items_to_copy;
        if (d_residual == 0) {
	  do { // Skip all those inputs with zero length
	    d_stream = (d_stream+1) % d_lengths.size();
	  } while (d_lengths[d_stream] == 0);
          d_residual = d_lengths[d_stream];
        } else {
          break;
        }
      } // while

      for (size_t i = 0; i < input_index.size(); i++) {
	consume((int) i, input_index[i]);
      }

      return out_index;
    } /* work */

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