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https://gitlab.isc.org/isc-projects/bind9.git
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92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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/*! \file */
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#include <inttypes.h>
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#include <stdio.h>
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#include <isc/lfsr.h>
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#include <isc/print.h>
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#include <isc/util.h>
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uint32_t state[1024 * 64];
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int
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main(int argc, char **argv) {
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isc_lfsr_t lfsr1, lfsr2;
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int i;
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uint32_t temp;
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UNUSED(argc);
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UNUSED(argv);
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/*
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* Verify that returned values are reproducible.
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*/
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isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
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for (i = 0; i < 32; i++) {
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isc_lfsr_generate(&lfsr1, &state[i], 4);
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printf("lfsr1: state[%2d] = %08x\n", i, state[i]);
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}
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isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
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for (i = 0; i < 32; i++) {
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isc_lfsr_generate(&lfsr1, &temp, 4);
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if (state[i] != temp) {
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printf("lfsr1: state[%2d] = %08x, "
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"but new state is %08x\n",
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i, state[i], temp);
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}
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}
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/*
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* Now do the same with skipping.
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*/
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isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
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for (i = 0; i < 32; i++) {
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isc_lfsr_generate(&lfsr1, &state[i], 4);
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isc_lfsr_skip(&lfsr1, 32);
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printf("lfsr1: state[%2d] = %08x\n", i, state[i]);
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}
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isc_lfsr_init(&lfsr1, 0, 32, 0x80000057U, 0, NULL, NULL);
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for (i = 0; i < 32; i++) {
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isc_lfsr_generate(&lfsr1, &temp, 4);
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isc_lfsr_skip(&lfsr1, 32);
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if (state[i] != temp) {
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printf("lfsr1: state[%2d] = %08x, "
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"but new state is %08x\n",
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i, state[i], temp);
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}
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}
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/*
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* Try to find the period of the LFSR.
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*
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* x^16 + x^5 + x^3 + x^2 + 1
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*/
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isc_lfsr_init(&lfsr2, 0, 16, 0x00008016U, 0, NULL, NULL);
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for (i = 0; i < 32; i++) {
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isc_lfsr_generate(&lfsr2, &state[i], 4);
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printf("lfsr2: state[%2d] = %08x\n", i, state[i]);
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}
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isc_lfsr_init(&lfsr2, 0, 16, 0x00008016U, 0, NULL, NULL);
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for (i = 0; i < 32; i++) {
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isc_lfsr_generate(&lfsr2, &temp, 4);
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if (state[i] != temp) {
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printf("lfsr2: state[%2d] = %08x, "
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"but new state is %08x\n",
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i, state[i], temp);
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}
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}
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return (0);
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}
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