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/* -*- c++ -*- */
/*
* Copyright 2008,2010,2012 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "additive_scrambler_bb_impl.h"
#include <gnuradio/io_signature.h>
namespace gr {
namespace digital {
additive_scrambler_bb::sptr additive_scrambler_bb::make(uint64_t mask,
uint64_t seed,
uint8_t len,
int64_t count,
uint8_t bits_per_byte,
const std::string& reset_tag_key)
{
return gnuradio::make_block_sptr<additive_scrambler_bb_impl>(
mask, seed, len, count, bits_per_byte, reset_tag_key);
}
additive_scrambler_bb_impl::additive_scrambler_bb_impl(uint64_t mask,
uint64_t seed,
uint8_t len,
int64_t count,
uint8_t bits_per_byte,
const std::string& reset_tag_key)
: sync_block("additive_scrambler_bb",
io_signature::make(1, 1, sizeof(unsigned char)),
io_signature::make(1, 1, sizeof(unsigned char))),
d_lfsr(mask, seed, len),
d_count(reset_tag_key.empty() ? count : -1),
d_bytes(0),
d_len(len),
d_seed(seed),
d_bits_per_byte(bits_per_byte),
d_reset_tag_key(pmt::string_to_symbol(reset_tag_key))
{
if (d_count < -1) {
throw std::invalid_argument("count must be non-negative!");
}
if (d_bits_per_byte < 1 || d_bits_per_byte > 8) {
throw std::invalid_argument("bits_per_byte must be in [1, 8]");
}
}
additive_scrambler_bb_impl::~additive_scrambler_bb_impl() {}
uint64_t additive_scrambler_bb_impl::mask() const { return d_lfsr.mask(); }
uint64_t additive_scrambler_bb_impl::seed() const { return d_seed; }
uint8_t additive_scrambler_bb_impl::len() const { return d_len; }
int64_t additive_scrambler_bb_impl::count() const { return d_count; }
int64_t
additive_scrambler_bb_impl::_get_next_reset_index(int64_t noutput_items,
int64_t last_reset_index /* = -1 */)
{
int64_t reset_index =
noutput_items; // This is a value that gets never reached in the for loop
if (d_count == -1) {
std::vector<gr::tag_t> tags;
get_tags_in_range(
tags, 0, nitems_read(0), nitems_read(0) + noutput_items, d_reset_tag_key);
for (unsigned i = 0; i < tags.size(); i++) {
int64_t reset_pos = tags[i].offset - nitems_read(0);
if (reset_pos < reset_index && reset_pos > last_reset_index) {
reset_index = reset_pos;
}
}
} else {
if (last_reset_index == -1) {
reset_index = d_count - d_bytes;
} else {
reset_index = last_reset_index + d_count;
}
}
return reset_index;
}
int additive_scrambler_bb_impl::work(int noutput_items,
gr_vector_const_void_star& input_items,
gr_vector_void_star& output_items)
{
const unsigned char* in = (const unsigned char*)input_items[0];
unsigned char* out = (unsigned char*)output_items[0];
int reset_index = _get_next_reset_index(noutput_items);
for (int i = 0; i < noutput_items; i++) {
// Reset should occur at/before the item associated with the tag.
if (i == reset_index) {
d_lfsr.reset();
d_bytes = 0;
reset_index = _get_next_reset_index(noutput_items, reset_index);
}
unsigned char scramble_byte = 0x00;
for (int k = 0; k < d_bits_per_byte; k++) {
scramble_byte ^= (d_lfsr.next_bit() << k);
}
out[i] = in[i] ^ scramble_byte;
d_bytes++;
}
return noutput_items;
}
} /* namespace digital */
} /* namespace gr */
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