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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: mpscan.h,v 1.3 1999/12/10 23:29:48 mdw Exp $ |
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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 $ |
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33 | * Revision 1.3 1999/12/10 23:29:48 mdw |
34 | * Change header file guard names. |
35 | * |
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36 | * Revision 1.2 1999/11/13 01:55:10 mdw |
37 | * Fixed so that they compile. Minor interface changes. |
38 | * |
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39 | * Revision 1.1 1999/09/03 08:41:12 mdw |
40 | * Initial import. |
41 | * |
42 | */ |
43 | |
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44 | #ifndef CATACOMB_MPSCAN_H |
45 | #define CATACOMB_MPSCAN_H |
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46 | |
47 | #ifdef __cplusplus |
48 | extern "C" { |
49 | #endif |
50 | |
51 | /*----- Header files ------------------------------------------------------*/ |
52 | |
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53 | #ifndef CATACOMB_MPW_H |
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54 | # include "mpw.h" |
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55 | #endif |
56 | |
57 | /*----- Data structures ---------------------------------------------------*/ |
58 | |
59 | typedef struct mpscan { |
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60 | const mpw *v, *vl; /* Vector of words to scan */ |
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61 | mpw w; /* Current word to scan */ |
62 | int bits; /* Number of bits left in @w@ */ |
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63 | } mpscan; |
64 | |
65 | /*----- Functions provided ------------------------------------------------*/ |
66 | |
67 | /* --- @mpscan_initx@ --- * |
68 | * |
69 | * Arguments: @mpscan *m@ = pointer to bitscanner structure |
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70 | * @const mpw *v, *vl@ = vector of words to scan |
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71 | * |
72 | * Returns: --- |
73 | * |
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74 | * Use: Initializes a bitscanner from a low-level base-and-limit |
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75 | * representation of an integer. Initially no bit is ready; you |
76 | * must call @mpscan_step@ before anything useful will come |
77 | * out. |
78 | */ |
79 | |
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80 | #define MPSCAN_INITX(m_, v_, vl_) do { \ |
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81 | mpscan *_m = (m_); \ |
82 | _m->v = (v_); \ |
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83 | _m->vl = (vl_); \ |
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84 | _m->bits = 0; \ |
85 | } while (0) |
86 | |
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87 | extern void mpscan_initx(mpscan */*m*/, const mpw */*v*/, const mpw */*vl*/); |
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88 | |
89 | /* --- @mpscan_step@ --- * |
90 | * |
91 | * Arguments: @mpscan *m@ = pointer to bitscanner |
92 | * |
93 | * Returns: Nonzero if there is another bit to read. |
94 | * |
95 | * Use: Steps on to the next bit in the integer. The macro version |
96 | * evaluates its argument multiple times. |
97 | */ |
98 | |
99 | #define MPSCAN_STEP(m) \ |
100 | ((m)->bits ? ((m)->w >>= 1, \ |
101 | (m)->bits--, 1) : \ |
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102 | (m)->v < (m)->vl ? ((m)->w = *(m)->v++, \ |
103 | (m)->bits = MPW_BITS - 1, 1) : \ |
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104 | 0) |
105 | |
106 | extern int mpscan_step(mpscan */*m*/); |
107 | |
108 | /* --- @mpscan_bit@ --- * |
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 | * bitscanner. |
116 | */ |
117 | |
118 | #define MPSCAN_BIT(m) ((m)->w & 1) |
119 | |
120 | extern int mpscan_bit(const mpscan */*m*/); |
121 | |
122 | /*----- That's all, folks -------------------------------------------------*/ |
123 | |
124 | #ifdef __cplusplus |
125 | } |
126 | #endif |
127 | |
128 | #endif |