git.distorted.org.uk Git - u/mdw/catacomb/blob - math/mpscan.c

   1 /* -*-c-*-
   2  *
   3  * Sequential bit scan of multiprecision integers
   4  *
   5  * (c) 1999 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 #include "mpscan.h"
  31
  32 /*----- Right-to-left scanning --------------------------------------------*/
  33
  34 /* --- @mpscan_initx@ --- *
  35  *
  36  * Arguments:   @mpscan *m@ = pointer to bitscanner structure
  37  *              @const mpw *v, *vl@ = vector of words to scan
  38  *
  39  * Returns:     ---
  40  *
  41  * Use:         Initializes a bitscanner from a low-level vector-and-length
  42  *              representation of an integer.  Initially no bit is ready; you
  43  *              must call @mpscan_step@ before anything useful will come
  44  *              out.
  45  */
  46
  47 void mpscan_initx(mpscan *m, const mpw *v, const mpw *vl)
  48 {
  49   MPSCAN_INITX(m, v, vl);
  50 }
  51
  52 /* --- @mpscan_step@ --- *
  53  *
  54  * Arguments:   @mpscan *m@ = pointer to bitscanner
  55  *
  56  * Returns:     Nonzero if there is another bit to read.
  57  *
  58  * Use:         Steps on to the next bit in the integer.  The macro version
  59  *              evaluates its argument multiple times.
  60  */
  61
  62 int mpscan_step(mpscan *m) { return (MPSCAN_STEP(m)); }
  63
  64 /* --- @mpscan_bit@ --- *
  65  *
  66  * Arguments:   @const mpscan *m@ = pointer to bitscanner
  67  *
  68  * Returns:     The value of the current bit.
  69  *
  70  * Use:         Reads the value of the current bit looked at by a
  71  *              bitscanner.
  72  */
  73
  74 int mpscan_bit(const mpscan *m) { return (MPSCAN_BIT(m)); }
  75
  76 /*----- Left-to right-scanning --------------------------------------------*/
  77
  78 /* --- @mpscan_rinitx@ --- *
  79  *
  80  * Arguments:   @mpscan *m@ = pointer to bitscanner structure
  81  *              @const mpw *v, *vl@ = vector of words to scan
  82  *
  83  * Returns:     ---
  84  *
  85  * Use:         Initializes a reverse bitscanner from a low-level
  86  *              vector-and-length representation of an integer.  Initially no
  87  *              bit is ready; you must call @mpscan_rstep@ before anything
  88  *              useful will come out.
  89  */
  90
  91 void mpscan_rinitx(mpscan *m, const mpw *v, const mpw *vl)
  92 {
  93   MPSCAN_RINITX(m, v, vl);
  94 }
  95
  96 /* --- @mpscan_rstep@ --- *
  97  *
  98  * Arguments:   @mpscan *m@ = pointer to bitscanner
  99  *
 100  * Returns:     Nonzero if there is another bit to read.
 101  *
 102  * Use:         Steps on to the next bit in the integer.  The macro version
 103  *              evaluates its argument multiple times.
 104  */
 105
 106 int mpscan_rstep(mpscan *m) { return (MPSCAN_RSTEP(m)); }
 107
 108 /* --- @mpscan_rbit@ --- *
 109  *
 110  * Arguments:   @const mpscan *m@ = pointer to bitscanner
 111  *
 112  * Returns:     The value of the current bit.
 113  *
 114  * Use:         Reads the value of the current bit looked at by a
 115  *              reverse bitscanner.
 116  */
 117
 118 int mpscan_rbit(const mpscan *m) { return (MPSCAN_RBIT(m)); }
 119
 120 /*----- That's all, folks -------------------------------------------------*/