d03ab969 |
1 | /* -*-c-*- |
2 | * |
962405ef |
3 | * $Id: mpscan.h,v 1.2 1999/11/13 01:55:10 mdw Exp $ |
d03ab969 |
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.h,v $ |
962405ef |
33 | * Revision 1.2 1999/11/13 01:55:10 mdw |
34 | * Fixed so that they compile. Minor interface changes. |
35 | * |
d03ab969 |
36 | * Revision 1.1 1999/09/03 08:41:12 mdw |
37 | * Initial import. |
38 | * |
39 | */ |
40 | |
41 | #ifndef MPSCAN_H |
42 | #define MPSCAN_H |
43 | |
44 | #ifdef __cplusplus |
45 | extern "C" { |
46 | #endif |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
962405ef |
50 | #ifndef MPW_H |
51 | # include "mpw.h" |
d03ab969 |
52 | #endif |
53 | |
54 | /*----- Data structures ---------------------------------------------------*/ |
55 | |
56 | typedef struct mpscan { |
962405ef |
57 | const mpw *v, *vl; /* Vector of words to scan */ |
d03ab969 |
58 | mpw w; /* Current word to scan */ |
59 | int bits; /* Number of bits left in @w@ */ |
d03ab969 |
60 | } mpscan; |
61 | |
62 | /*----- Functions provided ------------------------------------------------*/ |
63 | |
64 | /* --- @mpscan_initx@ --- * |
65 | * |
66 | * Arguments: @mpscan *m@ = pointer to bitscanner structure |
962405ef |
67 | * @const mpw *v, *vl@ = vector of words to scan |
d03ab969 |
68 | * |
69 | * Returns: --- |
70 | * |
962405ef |
71 | * Use: Initializes a bitscanner from a low-level base-and-limit |
d03ab969 |
72 | * representation of an integer. Initially no bit is ready; you |
73 | * must call @mpscan_step@ before anything useful will come |
74 | * out. |
75 | */ |
76 | |
962405ef |
77 | #define MPSCAN_INITX(m_, v_, vl_) do { \ |
d03ab969 |
78 | mpscan *_m = (m_); \ |
79 | _m->v = (v_); \ |
962405ef |
80 | _m->vl = (vl_); \ |
d03ab969 |
81 | _m->bits = 0; \ |
82 | } while (0) |
83 | |
962405ef |
84 | extern void mpscan_initx(mpscan */*m*/, const mpw */*v*/, const mpw */*vl*/); |
d03ab969 |
85 | |
86 | /* --- @mpscan_step@ --- * |
87 | * |
88 | * Arguments: @mpscan *m@ = pointer to bitscanner |
89 | * |
90 | * Returns: Nonzero if there is another bit to read. |
91 | * |
92 | * Use: Steps on to the next bit in the integer. The macro version |
93 | * evaluates its argument multiple times. |
94 | */ |
95 | |
96 | #define MPSCAN_STEP(m) \ |
97 | ((m)->bits ? ((m)->w >>= 1, \ |
98 | (m)->bits--, 1) : \ |
962405ef |
99 | (m)->v < (m)->vl ? ((m)->w = *(m)->v++, \ |
100 | (m)->bits = MPW_BITS - 1, 1) : \ |
d03ab969 |
101 | 0) |
102 | |
103 | extern int mpscan_step(mpscan */*m*/); |
104 | |
105 | /* --- @mpscan_bit@ --- * |
106 | * |
107 | * Arguments: @const mpscan *m@ = pointer to bitscanner |
108 | * |
109 | * Returns: The value of the current bit. |
110 | * |
111 | * Use: Reads the value of the current bit looked at by a |
112 | * bitscanner. |
113 | */ |
114 | |
115 | #define MPSCAN_BIT(m) ((m)->w & 1) |
116 | |
117 | extern int mpscan_bit(const mpscan */*m*/); |
118 | |
119 | /*----- That's all, folks -------------------------------------------------*/ |
120 | |
121 | #ifdef __cplusplus |
122 | } |
123 | #endif |
124 | |
125 | #endif |