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/* -*- c++ -*- */
/*
* Copyright 2005,2007 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.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <gr_skiphead.h>
#include <gr_io_signature.h>
gr_skiphead::gr_skiphead (size_t itemsize, size_t nitems_to_skip)
: gr_block ("skiphead",
gr_make_io_signature(1, 1, itemsize),
gr_make_io_signature(1, 1, itemsize)),
d_nitems_to_skip(nitems_to_skip), d_nitems(0)
{
}
gr_skiphead_sptr
gr_make_skiphead (size_t itemsize, size_t nitems_to_skip)
{
return gr_skiphead_sptr (new gr_skiphead (itemsize, nitems_to_skip));
}
int
gr_skiphead::general_work(int noutput_items,
gr_vector_int &ninput_items_ignored,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const char *in = (const char *) input_items[0];
char *out = (char *) output_items[0];
int ninput_items = noutput_items; // we've got at least this many input items
int ii = 0; // input index
while (ii < ninput_items){
long long ni_total = ii + d_nitems; // total items processed so far
if (ni_total < d_nitems_to_skip){ // need to skip some more
int n_to_skip = (int) std::min(d_nitems_to_skip - ni_total,
(long long)(ninput_items - ii));
ii += n_to_skip;
}
else { // nothing left to skip. copy away
int n_to_copy = ninput_items - ii;
if (n_to_copy > 0){
size_t itemsize = output_signature()->sizeof_stream_item(0);
memcpy(out, in + (ii*itemsize), n_to_copy*itemsize);
}
d_nitems += ninput_items;
consume_each(ninput_items);
return n_to_copy;
}
}
d_nitems += ninput_items;
consume_each(ninput_items);
return 0;
}
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