3 * Multiply many small numbers together
5 * (c) 2000 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
34 /*----- Main code ---------------------------------------------------------*/
36 /* --- @mpmul_init@ --- *
38 * Arguments: @mpmul *b@ = pointer to multiplier context to initialize
42 * Use: Initializes a big multiplier context for use.
45 void mpmul_init(mpmul
*b
)
50 /* --- @mpmul_add@ --- *
52 * Arguments: @mpmul *b@ = pointer to multiplier context
53 * @mp *x@ = the next factor to multiply in
57 * Use: Contributes another factor to the mix. It's important that
58 * the integer lasts at least as long as the multiplication
59 * context; this sort of rules out @mp_build@ integers.
62 #define HWM (MPMUL_DEPTH - 20)
63 #define LWM (MPMUL_DEPTH / 2)
65 void mpmul_add(mpmul
*b
, mp
*x
)
69 /* --- Now do the reduction step --- */
74 if (MP_LEN(b
->v
[i
- 1]) > MP_LEN(x
))
77 x
= mp_mul(x
, x
, b
->v
[i
]);
82 while (i
> LWM
|| (i
> 0 && MP_LEN(b
->v
[i
- 1]) <= MP_LEN(x
))) {
84 x
= mp_mul(x
, x
, b
->v
[i
]);
93 /* --- @mpmul_done@ --- *
95 * Arguments: @mpmul *b@ = pointer to big multiplication context
97 * Returns: The product of all the numbers contributed.
99 * Use: Returns a (large) product of numbers. The context is
103 mp
*mpmul_done(mpmul
*b
)
114 x
= mp_mul(x
, x
, b
->v
[i
]);
120 /* --- @mp_factorial@ --- *
122 * Arguments: @unsigned long i@ = number whose factorial should be
125 * Returns: The requested factorial.
128 mp
*mp_factorial(unsigned long i
)
132 mpmul b
= MPMUL_INIT
;
134 for (j
= 1; j
<= i
; j
++) {
135 x
= mp_fromulong(x
, j
);
139 return (mpmul_done(&b
));
142 /*----- Test rig ----------------------------------------------------------*/
146 #include <mLib/testrig.h>
148 static int vfact(dstr
*v
)
150 unsigned long x
= *(unsigned long *)v
[0].buf
;
151 mp
*fx
= *(mp
**)v
[1].buf
;
152 mp
*y
= mp_factorial(x
);
155 fprintf(stderr
, "factorial failed\n");
156 MP_FPRINTF(stderr
, (stderr
, "%lu! = ", x
), fx
);
157 MP_EPRINT("result", y
);
162 assert(mparena_count(MPARENA_GLOBAL
) == 0);
166 static test_chunk tests
[] = {
167 { "factorial", vfact
, { &type_ulong
, &type_mp
, 0 } },
171 int main(int argc
, char *argv
[])
173 test_run(argc
, argv
, tests
, SRCDIR
"/t/mp");
179 /*----- That's all, folks -------------------------------------------------*/