3 * $Id: mpscan.h,v 1.1 1999/09/03 08:41:12 mdw Exp $
5 * Sequential bit scan of multiprecision integers
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.1 1999/09/03 08:41:12 mdw
45 /*----- Header files ------------------------------------------------------*/
51 /*----- Data structures ---------------------------------------------------*/
53 typedef struct mpscan
{
54 const mpw
*v
; /* Vector of words to scan */
55 mpw w
; /* Current word to scan */
56 int bits
; /* Number of bits left in @w@ */
57 size_t len
; /* Length of the vector in words */
60 /*----- Functions provided ------------------------------------------------*/
62 /* --- @mpscan_initx@ --- *
64 * Arguments: @mpscan *m@ = pointer to bitscanner structure
65 * @const mpw *v@ = vector of words to scan
66 * @size_t len@ = length of vector in words
70 * Use: Initializes a bitscanner from a low-level vector-and-length
71 * representation of an integer. Initially no bit is ready; you
72 * must call @mpscan_step@ before anything useful will come
76 #define MPSCAN_INITX(m_, v_, len_) do { \
83 extern void mpscan_initx(mpscan */
*m*/
, const mpw */
*v*/
, size_t /*len*/);
85 /* --- @mpscan_step@ --- *
87 * Arguments: @mpscan *m@ = pointer to bitscanner
89 * Returns: Nonzero if there is another bit to read.
91 * Use: Steps on to the next bit in the integer. The macro version
92 * evaluates its argument multiple times.
95 #define MPSCAN_STEP(m) \
96 ((m)->bits ? ((m)->w >>= 1, \
98 (m)->len ? ((m)->len--, \
100 (m)->bits = MP_WBITS - 1, 1) : \
103 extern int mpscan_step(mpscan */
*m*/
);
105 /* --- @mpscan_bit@ --- *
107 * Arguments: @const mpscan *m@ = pointer to bitscanner
109 * Returns: The value of the current bit.
111 * Use: Reads the value of the current bit looked at by a
115 #define MPSCAN_BIT(m) ((m)->w & 1)
117 extern int mpscan_bit(const mpscan */
*m*/
);
119 /*----- That's all, folks -------------------------------------------------*/