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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
/*! \file */
#include <inttypes.h>
#include <stdio.h>
#include <isc/lfsr.h>
#include <isc/print.h>
#include <isc/util.h>
uint32_t state[1024 * 64];
int
main(int argc, char **argv) {
isc_lfsr_t lfsr1, lfsr2;
int i;
uint32_t temp;
UNUSED(argc);
UNUSED(argv);
/*
* Verify that returned values are reproducible.
*/
isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
for (i = 0; i < 32; i++) {
isc_lfsr_generate(&lfsr1, &state[i], 4);
printf("lfsr1: state[%2d] = %08x\n", i, state[i]);
}
isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
for (i = 0; i < 32; i++) {
isc_lfsr_generate(&lfsr1, &temp, 4);
if (state[i] != temp) {
printf("lfsr1: state[%2d] = %08x, "
"but new state is %08x\n",
i, state[i], temp);
}
}
/*
* Now do the same with skipping.
*/
isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
for (i = 0; i < 32; i++) {
isc_lfsr_generate(&lfsr1, &state[i], 4);
isc_lfsr_skip(&lfsr1, 32);
printf("lfsr1: state[%2d] = %08x\n", i, state[i]);
}
isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
for (i = 0; i < 32; i++) {
isc_lfsr_generate(&lfsr1, &temp, 4);
isc_lfsr_skip(&lfsr1, 32);
if (state[i] != temp) {
printf("lfsr1: state[%2d] = %08x, "
"but new state is %08x\n",
i, state[i], temp);
}
}
/*
* Try to find the period of the LFSR.
*
* x^16 + x^5 + x^3 + x^2 + 1
*/
isc_lfsr_init(&lfsr2, 0, 16, 0x00008016U, 0, NULL, NULL);
for (i = 0; i < 32; i++) {
isc_lfsr_generate(&lfsr2, &state[i], 4);
printf("lfsr2: state[%2d] = %08x\n", i, state[i]);
}
isc_lfsr_init(&lfsr2, 0, 16, 0x00008016U, 0, NULL, NULL);
for (i = 0; i < 32; i++) {
isc_lfsr_generate(&lfsr2, &temp, 4);
if (state[i] != temp) {
printf("lfsr2: state[%2d] = %08x, "
"but new state is %08x\n",
i, state[i], temp);
}
}
return (0);
}
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