xref: /titanic_41/usr/src/lib/libmp/common/pow.c (revision 7c478bd95313f5f23a4c958a745db2134aa03244)
1 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
2 /*	  All Rights Reserved  	*/
3 
4 
5 /*
6  * Copyright (c) 1980 Regents of the University of California.
7  * All rights reserved.  The Berkeley software License Agreement
8  * specifies the terms and conditions for redistribution.
9  */
10 /* 	Portions Copyright(c) 1988, Sun Microsystems Inc.	*/
11 /*	All Rights Reserved					*/
12 
13 /*
14  * Copyright (c) 1997, by Sun Microsystems, Inc.
15  * All rights reserved.
16  */
17 
18 #ident	"%Z%%M%	%I%	%E% SMI"	/* SVr4.0 1.1	*/
19 
20 #include <stdio.h>
21 #include <sys/types.h>
22 
23 /* LINTLIBRARY */
24 
25 #include <mp.h>
26 #include "libmp.h"
27 
28 void
mp_pow(MINT * a,MINT * b,MINT * c,MINT * d)29 mp_pow(MINT *a, MINT *b, MINT *c, MINT *d)
30 {
31 	int i, j, n;
32 	MINT x, y;
33 	MINT a0, b0, c0;
34 
35 	a0.len = b0.len = c0.len = x.len = y.len = 0;
36 	_mp_move(a, &a0);
37 	_mp_move(b, &b0);
38 	_mp_move(c, &c0);
39 	_mp_xfree(d);
40 	d->len = 1;
41 	d->val = _mp_xalloc(1, "mp_pow");
42 	*d->val = 1;
43 	for (j = 0; j < b0.len; j++) {
44 		n = b0.val[b0.len - j - 1];
45 		for (i = 0; i < 15; i++) {
46 			mp_mult(d, d, &x);
47 			mp_mdiv(&x, &c0, &y, d);
48 			if ((n = n << 1) & 0100000) {
49 				mp_mult(&a0, d, &x);
50 				mp_mdiv(&x, &c0, &y, d);
51 			}
52 		}
53 	}
54 	_mp_xfree(&x);
55 	_mp_xfree(&y);
56 	_mp_xfree(&a0);
57 	_mp_xfree(&b0);
58 	_mp_xfree(&c0);
59 }
60 
61 void
mp_rpow(MINT * a,short n,MINT * b)62 mp_rpow(MINT *a, short n, MINT *b)
63 {
64 	MINT x, y;
65 	int	i;
66 
67 	x.len = 1;
68 	x.val = _mp_xalloc(1, "mp_rpow");
69 	*x.val = n;
70 	y.len = n * a->len + 4;
71 	y.val = _mp_xalloc(y.len, "mp_rpow2");
72 	for (i = 0; i < y.len; i++)
73 		y.val[i] = 0;
74 	y.val[y.len - 1] = 010000;
75 	mp_pow(a, &x, &y, b);
76 	_mp_xfree(&x);
77 	_mp_xfree(&y);
78 }
79