| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Generalized exponentiation |
| 4 | * |
| 5 | * (c) 2001 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb; if not, write to the Free |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | /*----- Header files ------------------------------------------------------*/ |
| 29 | |
| 30 | #define EXP_TYPE /* Hack */ |
| 31 | #include "exp.h" |
| 32 | |
| 33 | /*----- Main code ---------------------------------------------------------*/ |
| 34 | |
| 35 | /* --- @exp_simulnext@ --- * |
| 36 | * |
| 37 | * Arguments: @exp_simul *e@ = pointer to state structure |
| 38 | * @size_t x@ = a current accumulator |
| 39 | * |
| 40 | * Returns: The next column of bits. |
| 41 | * |
| 42 | * Use: Scans the next column of bits for a simultaneous |
| 43 | * exponentiation. |
| 44 | */ |
| 45 | |
| 46 | size_t exp_simulnext(exp_simul *e, size_t x) |
| 47 | { |
| 48 | size_t i; |
| 49 | |
| 50 | /* --- Move to the next word along --- */ |
| 51 | |
| 52 | if (!e->b) { |
| 53 | e->o--; |
| 54 | for (i = 0; i < e->n; i++) |
| 55 | e->s[i].w = e->o < e->s[i].len ? e->s[i].v[e->o] : 0; |
| 56 | e->b = MPW_BITS; |
| 57 | } |
| 58 | |
| 59 | /* --- Scan out a column of bits --- */ |
| 60 | |
| 61 | for (i = 0; i < e->n; i++) { |
| 62 | x = (x << 1) | ((e->s[i].w >> (MPW_BITS - 1)) & 1u); |
| 63 | e->s[i].w <<= 1; |
| 64 | } |
| 65 | e->b--; |
| 66 | return (x); |
| 67 | } |
| 68 | |
| 69 | /*----- That's all, folks -------------------------------------------------*/ |