1 /* -*- c++ -*- */
2 /*
3 * Copyright 2005,2007,2010,2013 Free Software Foundation, Inc.
4 *
5 * This file is part of GNU Radio
6 *
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
10 * any later version.
11 *
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
21 */
22
23 #ifdef HAVE_CONFIG_H
24 #include <config.h>
25 #endif
26
27 #include "skiphead_impl.h"
28 #include <gnuradio/io_signature.h>
29 #include <string.h>
30
31 namespace gr {
32 namespace blocks {
33
make(size_t itemsize,uint64_t nitems_to_skip)34 skiphead::sptr skiphead::make(size_t itemsize, uint64_t nitems_to_skip)
35 {
36 return gnuradio::get_initial_sptr(new skiphead_impl(itemsize, nitems_to_skip));
37 }
38
skiphead_impl(size_t itemsize,uint64_t nitems_to_skip)39 skiphead_impl::skiphead_impl(size_t itemsize, uint64_t nitems_to_skip)
40 : block("skiphead",
41 io_signature::make(1, 1, itemsize),
42 io_signature::make(1, 1, itemsize)),
43 d_nitems_to_skip(nitems_to_skip),
44 d_nitems(0)
45 {
46 // Reserve space for a few tags to avoid constant re-allocation
47 // in the call to get_tags_in_window
48 d_tags.reserve(8);
49
50 // We'll handle propagating tags our selves to handle shifting offsets of tags
51 set_tag_propagation_policy(TPP_DONT);
52 }
53
~skiphead_impl()54 skiphead_impl::~skiphead_impl() {}
55
general_work(int noutput_items,gr_vector_int & ninput_items_,gr_vector_const_void_star & input_items,gr_vector_void_star & output_items)56 int skiphead_impl::general_work(int noutput_items,
57 gr_vector_int& ninput_items_,
58 gr_vector_const_void_star& input_items,
59 gr_vector_void_star& output_items)
60 {
61 const char* in = (const char*)input_items[0];
62 char* out = (char*)output_items[0];
63
64 int ninput_items = std::min(ninput_items_[0], noutput_items);
65 int ii = 0; // input index
66
67 while (ii < ninput_items) {
68 uint64_t ni_total = ii + d_nitems; // total items processed so far
69 if (ni_total < d_nitems_to_skip) { // need to skip some more
70
71 int n_to_skip =
72 (int)std::min(d_nitems_to_skip - ni_total, (uint64_t)(ninput_items - ii));
73 ii += n_to_skip;
74 }
75
76 else { // nothing left to skip. copy away
77 // Grab all tags in the window and shift their offsets appropriately
78 get_tags_in_window(d_tags, 0, ii, ninput_items);
79 for (std::vector<tag_t>::iterator it = d_tags.begin(); it != d_tags.end();
80 it++) {
81 (*it).offset -= d_nitems_to_skip;
82 add_item_tag(0, *it);
83 }
84 int n_to_copy = ninput_items - ii;
85 if (n_to_copy > 0) {
86 size_t itemsize = output_signature()->sizeof_stream_item(0);
87 memcpy(out, in + (ii * itemsize), n_to_copy * itemsize);
88 }
89
90 d_nitems += ninput_items;
91 consume_each(ninput_items);
92 return n_to_copy;
93 }
94 }
95
96 d_nitems += ninput_items;
97 consume_each(ninput_items);
98 return 0;
99 }
100
101 } /* namespace blocks */
102 } /* namespace gr */
103