gr_head.cc

gnuradio软件无线电源程序.现在的手机多基于软件无线电

/* -*- 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.
 */

#include <gr_head.h>
#include <gr_io_signature.h>

gr_head::gr_head (size_t sizeof_stream_item, int nitems)
  : gr_sync_block ("head",
		   gr_make_io_signature (1, 1, sizeof_stream_item),
		   gr_make_io_signature (1, 1, sizeof_stream_item)),
    d_nitems (nitems), d_ncopied_items (0)
{
}

gr_block_sptr
gr_make_head (size_t sizeof_stream_item, int nitems)
{
  return gr_block_sptr (new gr_head (sizeof_stream_item, nitems));
}

int
gr_head::work (int noutput_items,
		    gr_vector_const_void_star &input_items,
		    gr_vector_void_star &output_items)
{
  if (d_ncopied_items >= d_nitems)
    return -1;				// Done!

  unsigned n = std::min (d_nitems - d_ncopied_items, noutput_items);
  
  if (n == 0)
    return 0;

  memcpy (output_items[0], input_items[0], n * input_signature()->sizeof_stream_item (0));
  d_ncopied_items += n;

  return n;
}