| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: mpscan.c,v 1.3 2000/07/29 17:03:31 mdw Exp $ |
| 4 | * |
| 5 | * Sequential bit scan of multiprecision integers |
| 6 | * |
| 7 | * (c) 1999 Straylight/Edgeware |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of Catacomb. |
| 13 | * |
| 14 | * Catacomb is free software; you can redistribute it and/or modify |
| 15 | * it under the terms of the GNU Library General Public License as |
| 16 | * published by the Free Software Foundation; either version 2 of the |
| 17 | * License, or (at your option) any later version. |
| 18 | * |
| 19 | * Catacomb is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | * GNU Library General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU Library General Public |
| 25 | * License along with Catacomb; if not, write to the Free |
| 26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 27 | * MA 02111-1307, USA. |
| 28 | */ |
| 29 | |
| 30 | /*----- Revision history --------------------------------------------------* |
| 31 | * |
| 32 | * $Log: mpscan.c,v $ |
| 33 | * Revision 1.3 2000/07/29 17:03:31 mdw |
| 34 | * Add support for left-to-right bitscanning, for use in modular |
| 35 | * exponentiation. |
| 36 | * |
| 37 | * Revision 1.2 1999/11/13 01:55:10 mdw |
| 38 | * Fixed so that they compile. Minor interface changes. |
| 39 | * |
| 40 | * Revision 1.1 1999/09/03 08:41:12 mdw |
| 41 | * Initial import. |
| 42 | * |
| 43 | */ |
| 44 | |
| 45 | /*----- Header files ------------------------------------------------------*/ |
| 46 | |
| 47 | #include "mpscan.h" |
| 48 | |
| 49 | /*----- Right-to-left scanning --------------------------------------------*/ |
| 50 | |
| 51 | /* --- @mpscan_initx@ --- * |
| 52 | * |
| 53 | * Arguments: @mpscan *m@ = pointer to bitscanner structure |
| 54 | * @const mpw *v, *vl@ = vector of words to scan |
| 55 | * |
| 56 | * Returns: --- |
| 57 | * |
| 58 | * Use: Initializes a bitscanner from a low-level vector-and-length |
| 59 | * representation of an integer. Initially no bit is ready; you |
| 60 | * must call @mpscan_step@ before anything useful will come |
| 61 | * out. |
| 62 | */ |
| 63 | |
| 64 | void mpscan_initx(mpscan *m, const mpw *v, const mpw *vl) |
| 65 | { |
| 66 | MPSCAN_INITX(m, v, vl); |
| 67 | } |
| 68 | |
| 69 | /* --- @mpscan_step@ --- * |
| 70 | * |
| 71 | * Arguments: @mpscan *m@ = pointer to bitscanner |
| 72 | * |
| 73 | * Returns: Nonzero if there is another bit to read. |
| 74 | * |
| 75 | * Use: Steps on to the next bit in the integer. The macro version |
| 76 | * evaluates its argument multiple times. |
| 77 | */ |
| 78 | |
| 79 | int mpscan_step(mpscan *m) { return (MPSCAN_STEP(m)); } |
| 80 | |
| 81 | /* --- @mpscan_bit@ --- * |
| 82 | * |
| 83 | * Arguments: @const mpscan *m@ = pointer to bitscanner |
| 84 | * |
| 85 | * Returns: The value of the current bit. |
| 86 | * |
| 87 | * Use: Reads the value of the current bit looked at by a |
| 88 | * bitscanner. |
| 89 | */ |
| 90 | |
| 91 | int mpscan_bit(const mpscan *m) { return (MPSCAN_BIT(m)); } |
| 92 | |
| 93 | /*----- Left-to right-scanning --------------------------------------------*/ |
| 94 | |
| 95 | /* --- @mpscan_rinitx@ --- * |
| 96 | * |
| 97 | * Arguments: @mpscan *m@ = pointer to bitscanner structure |
| 98 | * @const mpw *v, *vl@ = vector of words to scan |
| 99 | * |
| 100 | * Returns: --- |
| 101 | * |
| 102 | * Use: Initializes a reverse bitscanner from a low-level |
| 103 | * vector-and-length representation of an integer. Initially no |
| 104 | * bit is ready; you must call @mpscan_rstep@ before anything |
| 105 | * useful will come out. |
| 106 | */ |
| 107 | |
| 108 | void mpscan_rinitx(mpscan *m, const mpw *v, const mpw *vl) |
| 109 | { |
| 110 | MPSCAN_RINITX(m, v, vl); |
| 111 | } |
| 112 | |
| 113 | /* --- @mpscan_rstep@ --- * |
| 114 | * |
| 115 | * Arguments: @mpscan *m@ = pointer to bitscanner |
| 116 | * |
| 117 | * Returns: Nonzero if there is another bit to read. |
| 118 | * |
| 119 | * Use: Steps on to the next bit in the integer. The macro version |
| 120 | * evaluates its argument multiple times. |
| 121 | */ |
| 122 | |
| 123 | int mpscan_rstep(mpscan *m) { return (MPSCAN_RSTEP(m)); } |
| 124 | |
| 125 | /* --- @mpscan_rbit@ --- * |
| 126 | * |
| 127 | * Arguments: @const mpscan *m@ = pointer to bitscanner |
| 128 | * |
| 129 | * Returns: The value of the current bit. |
| 130 | * |
| 131 | * Use: Reads the value of the current bit looked at by a |
| 132 | * reverse bitscanner. |
| 133 | */ |
| 134 | |
| 135 | int mpscan_rbit(const mpscan *m) { return (MPSCAN_RBIT(m)); } |
| 136 | |
| 137 | /*----- That's all, folks -------------------------------------------------*/ |