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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: mpint.h,v 1.2 1999/12/10 23:22:53 mdw Exp $ |
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4 | * |
5 | * Conversion between MPs and standard C 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: mpint.h,v $ |
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33 | * Revision 1.2 1999/12/10 23:22:53 mdw |
34 | * Support for uint32. |
35 | * |
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36 | * Revision 1.1 1999/11/25 11:38:31 mdw |
37 | * Support for conversions between MPs and C integers. |
38 | * |
39 | */ |
40 | |
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41 | #ifndef CATACOMB_MPINT_H |
42 | #define CATACOMB_MPINT_H |
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43 | |
44 | #ifdef __cplusplus |
45 | extern "C" { |
46 | #endif |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
50 | #include <limits.h> |
51 | |
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52 | #ifndef CATACOMB_MP_H |
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53 | # include "mp.h" |
54 | #endif |
55 | |
56 | /*----- Generic translation macros ----------------------------------------*/ |
57 | |
58 | /* --- @MP_FROMINT@ --- * |
59 | * |
60 | * Arguments: @d@ = destination multiprecision integer |
61 | * @type@ = type of integer which @i@ is |
62 | * @i@ = a standard C integer |
63 | * |
64 | * Use: Stores the value of @i@ in @d@. This macro is actually |
65 | * rather subtle in places. Be careful what you change. |
66 | */ |
67 | |
68 | #define MP_FROMINT(d, type, i) do { \ |
69 | type _i = (i); \ |
70 | size_t _o = 0; \ |
71 | mp *_d = (d); \ |
72 | size_t _sz = 4; \ |
73 | \ |
74 | MP_MODIFY(_d, _sz); \ |
75 | _d->f &= ~(MP_NEG | MP_UNDEF); \ |
76 | \ |
77 | /* --- Set the sign on the MP --- * \ |
78 | * \ |
79 | * If the input integer is *not* negative, then negate it. This \ |
80 | * fixes a problem with two's complement machines where the most \ |
81 | * negative value actually has larger magnitude than the most \ |
82 | * positive, and hence -TYPE_MIN == TYPE_MIN but TYPE_MIN != 0. If \ |
83 | * all the work is carried out on negative numbers there isn't a \ |
84 | * problem. \ |
85 | */ \ |
86 | \ |
87 | if (_i >= 0) \ |
88 | _i = -_i; \ |
89 | else \ |
90 | _d->f |= MP_NEG; \ |
91 | \ |
92 | while (_i) { \ |
93 | if (_o == _sz) { \ |
94 | _sz <<= 1; \ |
95 | MP_ENSURE(_d, _sz); \ |
96 | } \ |
97 | _d->v[_o++] = MPW(-_i); \ |
98 | \ |
99 | /* --- More subtlety --- * \ |
100 | * \ |
101 | * Ideally, I'd like to just shift @i@ right by @MPW_BITS@. But I \ |
102 | * can't, because that might be more than I'm allowed. I can't \ |
103 | * divide by @MPW_MAX + 1@ because that might turn out to be zero \ |
104 | * in my current type, and besides which it's unsigned which messes \ |
105 | * up all of my negative arithmetic. So do an explicit test here. \ |
106 | */ \ |
107 | \ |
108 | if (_i > -MPW_MAX) \ |
109 | break; \ |
110 | else \ |
111 | _i /= (type)MPW_MAX + 1; \ |
112 | } \ |
113 | _d->vl = _d->v + _o; \ |
114 | (d) = _d; \ |
115 | } while (0) |
116 | |
117 | /* --- @MP_TOINT@ --- * |
118 | * |
119 | * Arguments: @m@ = a multiprecision integer |
120 | * @type@ = the type of @i@ |
121 | * @max@ = the largest value @i@ can represent |
122 | * @i@ = an integer variable |
123 | * |
124 | * Use: Stores the value of a multiprecision integer in a standard C |
125 | * integer. If the value won't fit, the behaviour is determined |
126 | * by the type of @i@: if @i@ is unsigned, the value of the |
127 | * multiprecision integer modulo @max + 1@ is stored; if @i@ is |
128 | * signed, the behaviour is undefined. |
129 | * |
130 | * If you don't want to be bitten by these sorts of things, keep |
131 | * copies of @INT_MAX@ or whatever is appropriate in |
132 | * multiprecision form and compare before conversion. |
133 | */ |
134 | |
135 | #define MP_TOINT(m, type, max, i) do { \ |
136 | type _i = 0; \ |
137 | type _max = (max); \ |
138 | unsigned _s = 0; \ |
139 | const mp *_m = (m); \ |
140 | const mpw *_v = _m->v, *_vl = _m->vl; \ |
141 | \ |
142 | /* --- Do all the arithmetic in negative numbers --- */ \ |
143 | \ |
144 | while (_v < _vl && _max > 0) { \ |
145 | _i -= *_v << _s; \ |
146 | _s += MPW_BITS; \ |
147 | _v++; \ |
148 | _max /= (mpd)MPW_MAX + 1; \ |
149 | } \ |
150 | if (!(_m->f & MP_NEG)) \ |
151 | _i = -_i; \ |
152 | (i) = _i; \ |
153 | } while (0) |
154 | |
155 | /*----- Functions provided ------------------------------------------------*/ |
156 | |
157 | /* --- @mp_fromINT@ --- * |
158 | * |
159 | * Arguments: @mp *d@ = pointer to destination multiprecision integer |
160 | * @INT i@ = standard C integer to convert |
161 | * |
162 | * Returns: The resulting multiprecision integer. |
163 | * |
164 | * Use: Converts a standard C integer to a multiprecision integer. |
165 | */ |
166 | |
167 | #define mp_fromINT(name, type) \ |
168 | extern mp *mp_from##name(mp */*d*/, type /*i*/) |
169 | |
170 | mp_fromINT(short, short); |
171 | mp_fromINT(ushort, unsigned short); |
172 | mp_fromINT(int, int); |
173 | mp_fromINT(uint, unsigned); |
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174 | mp_fromINT(uint32, uint32); |
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175 | mp_fromINT(long, long); |
176 | mp_fromINT(ulong, unsigned long); |
177 | |
178 | #undef mp_fromINT |
179 | |
180 | /* --- @mp_toINT@ --- * |
181 | * |
182 | * Arguments: @const mp *m@ = pointer to a multiprecision integer |
183 | * |
184 | * Returns: The value of the integer @m@ as a C integer. |
185 | * |
186 | * Use: Converts a multiprecision integer to a standard C integer. |
187 | * If the value of the multiprecision integer cannot be |
188 | * represented in the return type, and the return type is |
189 | * unsigned, it is reduced modulo @TYPE_MAX + 1@; if the return |
190 | * type is signed, the behaviour is undefined. |
191 | */ |
192 | |
193 | #define mp_toINT(name, type) \ |
194 | extern type mp_to##name(const mp */*m*/); |
195 | |
196 | mp_toINT(short, short); |
197 | mp_toINT(ushort, unsigned short); |
198 | mp_toINT(int, int); |
199 | mp_toINT(uint, unsigned); |
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200 | mp_toINT(uint32, uint32); |
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201 | mp_toINT(long, long); |
202 | mp_toINT(ulong, unsigned long); |
203 | |
204 | #undef mp_toINT |
205 | |
206 | /*----- That's all, folks -------------------------------------------------*/ |
207 | |
208 | #ifdef __cplusplus |
209 | } |
210 | #endif |
211 | |
212 | #endif |