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Diffstat (limited to 'src/common/pearson.c')
| -rw-r--r-- | src/common/pearson.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/src/common/pearson.c b/src/common/pearson.c new file mode 100644 index 0000000..5607a0c --- /dev/null +++ b/src/common/pearson.c @@ -0,0 +1,106 @@ + +/* Chrysalide - Outil d'analyse de fichiers binaires + * pearson.c - implémentaton du calcul rapide d'empreintes de chaînes + * + * Copyright (C) 2021 Cyrille Bagard + * + * This file is part of Chrysalide. + * + * Chrysalide is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 3 of the License, or + * (at your option) any later version. + * + * Chrysalide is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with Chrysalide. If not, see <http://www.gnu.org/licenses/>. + */ + + +#include "pearson.h" + + +#include <stddef.h> + + + +/* Permutations proposées */ +static const char _pearson_permutations[256] = { + + 1, 87, 49, 12, 176, 178, 102, 166, 121, 193, 6, 84, 249, 230, 44, 163, + 14, 197, 213, 181, 161, 85, 218, 80, 64, 239, 24, 226, 236, 142, 38, 200, + 110, 177, 104, 103, 141, 253, 255, 50, 77, 101, 81, 18, 45, 96, 31, 222, + 25, 107, 190, 70, 86, 237, 240, 34, 72, 242, 20, 214, 244, 227, 149, 235, + 97, 234, 57, 22, 60, 250, 82, 175, 208, 5, 127, 199, 111, 62, 135, 248, + 174, 169, 211, 58, 66, 154, 106, 195, 245, 171, 17, 187, 182, 179, 0, 243, + 132, 56, 148, 75, 128, 133, 158, 100, 130, 126, 91, 13, 153, 246, 216, 219, + 119, 68, 223, 78, 83, 88, 201, 99, 122, 11, 92, 32, 136, 114, 52, 10, + 138, 30, 48, 183, 156, 35, 61, 26, 143, 74, 251, 94, 129, 162, 63, 152, + 170, 7, 115, 167, 241, 206, 3, 150, 55, 59, 151, 220, 90, 53, 23, 131, + 125, 173, 15, 238, 79, 95, 89, 16, 105, 137, 225, 224, 217, 160, 37, 123, + 118, 73, 2, 157, 46, 116, 9, 145, 134, 228, 207, 212, 202, 215, 69, 229, + 27, 188, 67, 124, 168, 252, 42, 4, 29, 108, 21, 247, 19, 205, 39, 203, + 233, 40, 186, 147, 198, 192, 155, 33, 164, 191, 98, 204, 165, 180, 117, 76, + 140, 36, 210, 172, 41, 54, 159, 8, 185, 232, 113, 196, 231, 47, 146, 120, + 51, 65, 28, 144, 254, 221, 93, 189, 194, 139, 112, 43, 71, 109, 184, 209 + +}; + + + +/****************************************************************************** +* * +* Paramètres : - * +* * +* Description : Fournit les permutations par défaut par Pearson. * +* * +* Retour : Table de valeurs utilisées par défaut. * +* * +* Remarques : - * +* * +******************************************************************************/ + +const char *get_pearson_permutations(void) +{ + const char *result; /* Table à renvoyer */ + + result = _pearson_permutations; + + return result; + +} + + +/****************************************************************************** +* * +* Paramètres : str = chaîne de caractères à traiter. * +* table = permutations à employer, NULL pour celles par défaut.* +* * +* Description : Détermine l'empreinte Pearson d'une chaîne de caractères. * +* * +* Retour : Valeur calculée. * +* * +* Remarques : - * +* * +******************************************************************************/ + +uint8_t pearson_hash(const char *str, const char *table) +{ + uint8_t result; /* Valeur à retourner */ + unsigned char *iter; /* Boucle de parcours */ + + if (table == NULL) + table = _pearson_permutations; + + result = 0; + + for (iter = (unsigned char *)str; *iter; iter++) + result = table[result ^ (*iter)]; + + return result; + +} |