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comparison: security/nss/lib/freebl/mpi/utils/fact.c
security/nss/lib/freebl/mpi/utils/fact.c
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
equal
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| -1:000000000000 | 0:8afa02605a5c |
|---|---|
| 1 /* | |
| 2 * fact.c | |
| 3 * | |
| 4 * Compute factorial of input integer | |
| 5 * | |
| 6 * This Source Code Form is subject to the terms of the Mozilla Public | |
| 7 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 8 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 9 | |
| 10 #include <stdio.h> | |
| 11 #include <stdlib.h> | |
| 12 #include <string.h> | |
| 13 | |
| 14 #include "mpi.h" | |
| 15 | |
| 16 mp_err mp_fact(mp_int *a, mp_int *b); | |
| 17 | |
| 18 int main(int argc, char *argv[]) | |
| 19 { | |
| 20 mp_int a; | |
| 21 mp_err res; | |
| 22 | |
| 23 if(argc < 2) { | |
| 24 fprintf(stderr, "Usage: %s <number>\n", argv[0]); | |
| 25 return 1; | |
| 26 } | |
| 27 | |
| 28 mp_init(&a); | |
| 29 mp_read_radix(&a, argv[1], 10); | |
| 30 | |
| 31 if((res = mp_fact(&a, &a)) != MP_OKAY) { | |
| 32 fprintf(stderr, "%s: error: %s\n", argv[0], | |
| 33 mp_strerror(res)); | |
| 34 mp_clear(&a); | |
| 35 return 1; | |
| 36 } | |
| 37 | |
| 38 { | |
| 39 char *buf; | |
| 40 int len; | |
| 41 | |
| 42 len = mp_radix_size(&a, 10); | |
| 43 buf = malloc(len); | |
| 44 mp_todecimal(&a, buf); | |
| 45 | |
| 46 puts(buf); | |
| 47 | |
| 48 free(buf); | |
| 49 } | |
| 50 | |
| 51 mp_clear(&a); | |
| 52 return 0; | |
| 53 } | |
| 54 | |
| 55 mp_err mp_fact(mp_int *a, mp_int *b) | |
| 56 { | |
| 57 mp_int ix, s; | |
| 58 mp_err res = MP_OKAY; | |
| 59 | |
| 60 if(mp_cmp_z(a) < 0) | |
| 61 return MP_UNDEF; | |
| 62 | |
| 63 mp_init(&s); | |
| 64 mp_add_d(&s, 1, &s); /* s = 1 */ | |
| 65 mp_init(&ix); | |
| 66 mp_add_d(&ix, 1, &ix); /* ix = 1 */ | |
| 67 | |
| 68 for(/* */; mp_cmp(&ix, a) <= 0; mp_add_d(&ix, 1, &ix)) { | |
| 69 if((res = mp_mul(&s, &ix, &s)) != MP_OKAY) | |
| 70 break; | |
| 71 } | |
| 72 | |
| 73 mp_clear(&ix); | |
| 74 | |
| 75 /* Copy out results if we got them */ | |
| 76 if(res == MP_OKAY) | |
| 77 mp_copy(&s, b); | |
| 78 | |
| 79 mp_clear(&s); | |
| 80 | |
| 81 return res; | |
| 82 } |
