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

   1 /* -*-c-*-
   2  *
   3  * $Id: mpscan.c,v 1.4 2004/04/08 01:36:15 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 /*----- Header files ------------------------------------------------------*/
  31
  32 #include "mpscan.h"
  33
  34 /*----- Right-to-left scanning --------------------------------------------*/
  35
  36 /* --- @mpscan_initx@ --- *
  37  *
  38  * Arguments:   @mpscan *m@ = pointer to bitscanner structure
  39  *              @const mpw *v, *vl@ = vector of words to scan
  40  *
  41  * Returns:     ---
  42  *
  43  * Use:         Initializes a bitscanner from a low-level vector-and-length
  44  *              representation of an integer.  Initially no bit is ready; you
  45  *              must call @mpscan_step@ before anything useful will come
  46  *              out.
  47  */
  48
  49 void mpscan_initx(mpscan *m, const mpw *v, const mpw *vl)
  50 {
  51   MPSCAN_INITX(m, v, vl);
  52 }
  53
  54 /* --- @mpscan_step@ --- *
  55  *
  56  * Arguments:   @mpscan *m@ = pointer to bitscanner
  57  *
  58  * Returns:     Nonzero if there is another bit to read.
  59  *
  60  * Use:         Steps on to the next bit in the integer.  The macro version
  61  *              evaluates its argument multiple times.
  62  */
  63
  64 int mpscan_step(mpscan *m) { return (MPSCAN_STEP(m)); }
  65
  66 /* --- @mpscan_bit@ --- *
  67  *
  68  * Arguments:   @const mpscan *m@ = pointer to bitscanner
  69  *
  70  * Returns:     The value of the current bit.
  71  *
  72  * Use:         Reads the value of the current bit looked at by a
  73  *              bitscanner.
  74  */
  75
  76 int mpscan_bit(const mpscan *m) { return (MPSCAN_BIT(m)); }
  77
  78 /*----- Left-to right-scanning --------------------------------------------*/
  79
  80 /* --- @mpscan_rinitx@ --- *
  81  *
  82  * Arguments:   @mpscan *m@ = pointer to bitscanner structure
  83  *              @const mpw *v, *vl@ = vector of words to scan
  84  *
  85  * Returns:     ---
  86  *
  87  * Use:         Initializes a reverse bitscanner from a low-level
  88  *              vector-and-length representation of an integer.  Initially no
  89  *              bit is ready; you must call @mpscan_rstep@ before anything
  90  *              useful will come out.
  91  */
  92
  93 void mpscan_rinitx(mpscan *m, const mpw *v, const mpw *vl)
  94 {
  95   MPSCAN_RINITX(m, v, vl);
  96 }
  97
  98 /* --- @mpscan_rstep@ --- *
  99  *
 100  * Arguments:   @mpscan *m@ = pointer to bitscanner
 101  *
 102  * Returns:     Nonzero if there is another bit to read.
 103  *
 104  * Use:         Steps on to the next bit in the integer.  The macro version
 105  *              evaluates its argument multiple times.
 106  */
 107
 108 int mpscan_rstep(mpscan *m) { return (MPSCAN_RSTEP(m)); }
 109
 110 /* --- @mpscan_rbit@ --- *
 111  *
 112  * Arguments:   @const mpscan *m@ = pointer to bitscanner
 113  *
 114  * Returns:     The value of the current bit.
 115  *
 116  * Use:         Reads the value of the current bit looked at by a
 117  *              reverse bitscanner.
 118  */
 119
 120 int mpscan_rbit(const mpscan *m) { return (MPSCAN_RBIT(m)); }
 121
 122 /*----- That's all, folks -------------------------------------------------*/