forked from OSchip/llvm-project
97 lines
3.6 KiB
C
97 lines
3.6 KiB
C
/*
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Name: iprime.c
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Purpose: Pseudoprimality testing routines
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Author: M. J. Fromberger
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Copyright (C) 2002-2008 Michael J. Fromberger, All Rights Reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#include "iprime.h"
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#include <stdlib.h>
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static int s_ptab[] = {
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2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47,
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53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113,
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127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197,
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199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281,
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283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379,
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383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463,
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467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571,
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577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659,
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661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761,
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769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863,
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877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977,
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983, 991, 997, 0, /* sentinel */
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};
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mp_result mp_int_is_prime(mp_int z) {
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/* Reject values less than 2 immediately. */
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if (mp_int_compare_value(z, 2) < 0) {
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return MP_FALSE;
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}
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/* First check for divisibility by small primes; this eliminates a large
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number of composite candidates quickly
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*/
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for (int i = 0; s_ptab[i] != 0; i++) {
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mp_small rem;
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mp_result res;
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if (mp_int_compare_value(z, s_ptab[i]) == 0) return MP_TRUE;
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if ((res = mp_int_div_value(z, s_ptab[i], NULL, &rem)) != MP_OK) return res;
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if (rem == 0) return MP_FALSE;
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}
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/* Now try Fermat's test for several prime witnesses (since we now know from
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the above that z is not a multiple of any of them)
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*/
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mp_result res;
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mpz_t tmp;
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if ((res = mp_int_init(&tmp)) != MP_OK) return res;
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for (int i = 0; i < 10 && s_ptab[i] != 0; i++) {
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if ((res = mp_int_exptmod_bvalue(s_ptab[i], z, z, &tmp)) != MP_OK) {
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return res;
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}
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if (mp_int_compare_value(&tmp, s_ptab[i]) != 0) {
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mp_int_clear(&tmp);
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return MP_FALSE;
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}
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}
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mp_int_clear(&tmp);
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return MP_TRUE;
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}
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/* Find the first apparent prime in ascending order from z */
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mp_result mp_int_find_prime(mp_int z) {
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mp_result res;
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if (mp_int_is_even(z) && ((res = mp_int_add_value(z, 1, z)) != MP_OK))
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return res;
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while ((res = mp_int_is_prime(z)) == MP_FALSE) {
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if ((res = mp_int_add_value(z, 2, z)) != MP_OK) break;
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}
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return res;
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}
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/* Here there be dragons */
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