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1 | /* -*-c-*- |
2 | * |
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3 | * $Id$ |
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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 | |
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30 | #ifndef CATACOMB_MPINT_H |
31 | #define CATACOMB_MPINT_H |
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32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #include <limits.h> |
40 | |
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41 | #ifndef CATACOMB_MP_H |
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42 | # include "mp.h" |
43 | #endif |
44 | |
45 | /*----- Generic translation macros ----------------------------------------*/ |
46 | |
47 | /* --- @MP_FROMINT@ --- * |
48 | * |
49 | * Arguments: @d@ = destination multiprecision integer |
50 | * @type@ = type of integer which @i@ is |
51 | * @i@ = a standard C integer |
52 | * |
53 | * Use: Stores the value of @i@ in @d@. This macro is actually |
54 | * rather subtle in places. Be careful what you change. |
55 | */ |
56 | |
57 | #define MP_FROMINT(d, type, i) do { \ |
58 | type _i = (i); \ |
59 | size_t _o = 0; \ |
60 | mp *_d = (d); \ |
61 | size_t _sz = 4; \ |
62 | \ |
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63 | MP_DEST(_d, _sz, 0); \ |
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64 | _d->f &= ~(MP_NEG | MP_UNDEF); \ |
65 | \ |
66 | /* --- Set the sign on the MP --- * \ |
67 | * \ |
68 | * If the input integer is *not* negative, then negate it. This \ |
69 | * fixes a problem with two's complement machines where the most \ |
70 | * negative value actually has larger magnitude than the most \ |
71 | * positive, and hence -TYPE_MIN == TYPE_MIN but TYPE_MIN != 0. If \ |
72 | * all the work is carried out on negative numbers there isn't a \ |
73 | * problem. \ |
74 | */ \ |
75 | \ |
76 | if (_i >= 0) \ |
77 | _i = -_i; \ |
78 | else \ |
79 | _d->f |= MP_NEG; \ |
80 | \ |
81 | while (_i) { \ |
82 | if (_o == _sz) { \ |
83 | _sz <<= 1; \ |
84 | MP_ENSURE(_d, _sz); \ |
85 | } \ |
86 | _d->v[_o++] = MPW(-_i); \ |
87 | \ |
88 | /* --- More subtlety --- * \ |
89 | * \ |
90 | * Ideally, I'd like to just shift @i@ right by @MPW_BITS@. But I \ |
91 | * can't, because that might be more than I'm allowed. I can't \ |
92 | * divide by @MPW_MAX + 1@ because that might turn out to be zero \ |
93 | * in my current type, and besides which it's unsigned which messes \ |
94 | * up all of my negative arithmetic. So do an explicit test here. \ |
95 | */ \ |
96 | \ |
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97 | if (_i >= -MPW_MAX) \ |
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98 | break; \ |
99 | else \ |
100 | _i /= (type)MPW_MAX + 1; \ |
101 | } \ |
102 | _d->vl = _d->v + _o; \ |
103 | (d) = _d; \ |
104 | } while (0) |
105 | |
106 | /* --- @MP_TOINT@ --- * |
107 | * |
108 | * Arguments: @m@ = a multiprecision integer |
109 | * @type@ = the type of @i@ |
110 | * @max@ = the largest value @i@ can represent |
111 | * @i@ = an integer variable |
112 | * |
113 | * Use: Stores the value of a multiprecision integer in a standard C |
114 | * integer. If the value won't fit, the behaviour is determined |
115 | * by the type of @i@: if @i@ is unsigned, the value of the |
116 | * multiprecision integer modulo @max + 1@ is stored; if @i@ is |
117 | * signed, the behaviour is undefined. |
118 | * |
119 | * If you don't want to be bitten by these sorts of things, keep |
120 | * copies of @INT_MAX@ or whatever is appropriate in |
121 | * multiprecision form and compare before conversion. |
122 | */ |
123 | |
124 | #define MP_TOINT(m, type, max, i) do { \ |
125 | type _i = 0; \ |
126 | type _max = (max); \ |
127 | unsigned _s = 0; \ |
128 | const mp *_m = (m); \ |
129 | const mpw *_v = _m->v, *_vl = _m->vl; \ |
130 | \ |
131 | /* --- Do all the arithmetic in negative numbers --- */ \ |
132 | \ |
133 | while (_v < _vl && _max > 0) { \ |
134 | _i -= *_v << _s; \ |
135 | _s += MPW_BITS; \ |
136 | _v++; \ |
137 | _max /= (mpd)MPW_MAX + 1; \ |
138 | } \ |
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139 | if (!MP_NEGP(_m)) \ |
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140 | _i = -_i; \ |
141 | (i) = _i; \ |
142 | } while (0) |
143 | |
144 | /*----- Functions provided ------------------------------------------------*/ |
145 | |
146 | /* --- @mp_fromINT@ --- * |
147 | * |
148 | * Arguments: @mp *d@ = pointer to destination multiprecision integer |
149 | * @INT i@ = standard C integer to convert |
150 | * |
151 | * Returns: The resulting multiprecision integer. |
152 | * |
153 | * Use: Converts a standard C integer to a multiprecision integer. |
154 | */ |
155 | |
156 | #define mp_fromINT(name, type) \ |
157 | extern mp *mp_from##name(mp */*d*/, type /*i*/) |
158 | |
159 | mp_fromINT(short, short); |
160 | mp_fromINT(ushort, unsigned short); |
161 | mp_fromINT(int, int); |
162 | mp_fromINT(uint, unsigned); |
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163 | mp_fromINT(uint32, uint32); |
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164 | mp_fromINT(long, long); |
165 | mp_fromINT(ulong, unsigned long); |
166 | |
167 | #undef mp_fromINT |
168 | |
169 | /* --- @mp_toINT@ --- * |
170 | * |
171 | * Arguments: @const mp *m@ = pointer to a multiprecision integer |
172 | * |
173 | * Returns: The value of the integer @m@ as a C integer. |
174 | * |
175 | * Use: Converts a multiprecision integer to a standard C integer. |
176 | * If the value of the multiprecision integer cannot be |
177 | * represented in the return type, and the return type is |
178 | * unsigned, it is reduced modulo @TYPE_MAX + 1@; if the return |
179 | * type is signed, the behaviour is undefined. |
180 | */ |
181 | |
182 | #define mp_toINT(name, type) \ |
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183 | extern type mp_to##name(const mp */*m*/) |
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184 | |
185 | mp_toINT(short, short); |
186 | mp_toINT(ushort, unsigned short); |
187 | mp_toINT(int, int); |
188 | mp_toINT(uint, unsigned); |
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189 | mp_toINT(uint32, uint32); |
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190 | mp_toINT(long, long); |
191 | mp_toINT(ulong, unsigned long); |
192 | |
193 | #undef mp_toINT |
194 | |
195 | /*----- That's all, folks -------------------------------------------------*/ |
196 | |
197 | #ifdef __cplusplus |
198 | } |
199 | #endif |
200 | |
201 | #endif |