1 b3f61791 2004-03-21 devnull #include "os.h"
 2 b3f61791 2004-03-21 devnull #include <mp.h>
 3 b3f61791 2004-03-21 devnull #include "dat.h"
 4 b3f61791 2004-03-21 devnull 
 5 cbeb0b26 2006-04-01 devnull /* diff = abs(b1) - abs(b2), i.e., subtract the magnitudes */
 6 b3f61791 2004-03-21 devnull void
 7 b3f61791 2004-03-21 devnull mpmagsub(mpint *b1, mpint *b2, mpint *diff)
 8 b3f61791 2004-03-21 devnull {
 9 b3f61791 2004-03-21 devnull 	int n, m, sign;
10 b3f61791 2004-03-21 devnull 	mpint *t;
11 b3f61791 2004-03-21 devnull 
12 cbeb0b26 2006-04-01 devnull 	/* get the sizes right */
13 b3f61791 2004-03-21 devnull 	if(mpmagcmp(b1, b2) < 0){
14 b3f61791 2004-03-21 devnull 		sign = -1;
15 b3f61791 2004-03-21 devnull 		t = b1;
16 b3f61791 2004-03-21 devnull 		b1 = b2;
17 b3f61791 2004-03-21 devnull 		b2 = t;
18 b3f61791 2004-03-21 devnull 	} else
19 b3f61791 2004-03-21 devnull 		sign = 1;
20 b3f61791 2004-03-21 devnull 	n = b1->top;
21 b3f61791 2004-03-21 devnull 	m = b2->top;
22 b3f61791 2004-03-21 devnull 	if(m == 0){
23 b3f61791 2004-03-21 devnull 		mpassign(b1, diff);
24 b3f61791 2004-03-21 devnull 		diff->sign = sign;
25 b3f61791 2004-03-21 devnull 		return;
26 b3f61791 2004-03-21 devnull 	}
27 b3f61791 2004-03-21 devnull 	mpbits(diff, n*Dbits);
28 b3f61791 2004-03-21 devnull 
29 b3f61791 2004-03-21 devnull 	mpvecsub(b1->p, n, b2->p, m, diff->p);
30 b3f61791 2004-03-21 devnull 	diff->sign = sign;
31 b3f61791 2004-03-21 devnull 	diff->top = n;
32 b3f61791 2004-03-21 devnull 	mpnorm(diff);
33 b3f61791 2004-03-21 devnull }
34 b3f61791 2004-03-21 devnull 
35 cbeb0b26 2006-04-01 devnull /* diff = b1 - b2 */
36 b3f61791 2004-03-21 devnull void
37 b3f61791 2004-03-21 devnull mpsub(mpint *b1, mpint *b2, mpint *diff)
38 b3f61791 2004-03-21 devnull {
39 b3f61791 2004-03-21 devnull 	int sign;
40 b3f61791 2004-03-21 devnull 
41 b3f61791 2004-03-21 devnull 	if(b1->sign != b2->sign){
42 b3f61791 2004-03-21 devnull 		sign = b1->sign;
43 b3f61791 2004-03-21 devnull 		mpmagadd(b1, b2, diff);
44 b3f61791 2004-03-21 devnull 		diff->sign = sign;
45 b3f61791 2004-03-21 devnull 		return;
46 b3f61791 2004-03-21 devnull 	}
47 b3f61791 2004-03-21 devnull 
48 b3f61791 2004-03-21 devnull 	sign = b1->sign;
49 b3f61791 2004-03-21 devnull 	mpmagsub(b1, b2, diff);
50 b3f61791 2004-03-21 devnull 	if(diff->top != 0)
51 b3f61791 2004-03-21 devnull 		diff->sign *= sign;
52 b3f61791 2004-03-21 devnull }