5 * Conversion between MPs and standard C 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 #ifndef CATACOMB_MPINT_H
31 #define CATACOMB_MPINT_H
37 /*----- Header files ------------------------------------------------------*/
45 /*----- Generic translation macros ----------------------------------------*/
47 /* --- @MP_FROMINT@ --- *
49 * Arguments: @d@ = destination multiprecision integer
50 * @type@ = type of integer which @i@ is
51 * @i@ = a standard C integer
53 * Use: Stores the value of @i@ in @d@. This macro is actually
54 * rather subtle in places. Be careful what you change.
57 #define MP_FROMINT(d, type, i) do { \
63 MP_DEST(_d, _sz, 0); \
64 _d->f &= ~(MP_NEG | MP_UNDEF); \
66 /* --- Set the sign on the MP --- * \
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 \
86 _d->v[_o++] = MPW(-_i); \
88 /* --- More subtlety --- * \
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. \
100 _i /= (type)MPW_MAX + 1; \
102 _d->vl = _d->v + _o; \
106 /* --- @MP_TOINT@ --- *
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
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.
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.
124 #define MP_TOINT(m, type, max, i) do { \
128 const mp *_m = (m); \
129 const mpw *_v = _m->v, *_vl = _m->vl; \
131 /* --- Do all the arithmetic in negative numbers --- */ \
133 while (_v < _vl && _max > 0) { \
137 _max /= (mpd)MPW_MAX + 1; \
144 /*----- Functions provided ------------------------------------------------*/
146 /* --- @mp_fromINT@ --- *
148 * Arguments: @mp *d@ = pointer to destination multiprecision integer
149 * @INT i@ = standard C integer to convert
151 * Returns: The resulting multiprecision integer.
153 * Use: Converts a standard C integer to a multiprecision integer.
156 #define mp_fromINT(name, type) \
157 extern mp *mp_from##name(mp */*d*/, type /*i*/)
159 mp_fromINT(short, short);
160 mp_fromINT(ushort
, unsigned short);
161 mp_fromINT(int, int);
162 mp_fromINT(uint
, unsigned);
163 mp_fromINT(uint32
, uint32
);
164 mp_fromINT(long, long);
165 mp_fromINT(ulong
, unsigned long);
169 /* --- @mp_toINT@ --- *
171 * Arguments: @const mp *m@ = pointer to a multiprecision integer
173 * Returns: The value of the integer @m@ as a C integer.
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.
182 #define mp_toINT(name, type) \
183 extern type mp_to##name(const mp */*m*/)
185 mp_toINT(short, short);
186 mp_toINT(ushort
, unsigned short);
188 mp_toINT(uint
, unsigned);
189 mp_toINT(uint32
, uint32
);
190 mp_toINT(long, long);
191 mp_toINT(ulong
, unsigned long);
195 /*----- That's all, folks -------------------------------------------------*/