1 /*- 2 * %sccs.include.proprietary.c% 3 */ 4 5 #ifndef lint 6 static char sccsid[] = "@(#)mult.c 8.1 (Berkeley) 06/04/93"; 7 #endif /* not lint */ 8 9 #include <mp.h> 10 mult(a,b,c) struct mint *a,*b,*c; 11 { struct mint x,y,z; 12 int sign; 13 sign = 1; 14 x.val=a->val; 15 y.val=b->val; 16 z.len=0; 17 if(a->len<0) 18 { x.len= -a->len; 19 sign= -sign; 20 } 21 else x.len=a->len; 22 if(b->len<0) 23 { y.len= -b->len; 24 sign= -sign; 25 } 26 else y.len=b->len; 27 if(x.len<y.len) m_mult(&y,&x,&z); 28 else m_mult(&x,&y,&z); 29 xfree(c); 30 if(sign<0) c->len= -z.len; 31 else c->len=z.len; 32 if(c->len==0) shfree(z.val); 33 else c->val=z.val; 34 return; 35 } 36 #define S2 x=a->val[j]; 37 #define S3 x=x*b->val[i-j]; 38 #define S4 tradd(&carry,&sum,x); 39 #define S5 c->val[i]=sum.yy.low&077777; 40 #define S6 sum.xx=sum.xx>>15; 41 #define S7 sum.yy.high=carry; 42 m_mult(a,b,c) struct mint *a,*b,*c; 43 { long x; 44 union {long xx; struct half yy;} sum; 45 int carry; 46 int i,j; 47 c->val=xalloc(a->len+b->len,"m_mult"); 48 sum.xx=0; 49 for(i=0;i<b->len;i++) 50 { carry=0; 51 for(j=0;j<i+1;j++) 52 { S2 53 S3 54 S4 55 } 56 S5 57 S6 58 S7 59 } 60 for(;i<a->len;i++) 61 { carry=0; 62 for(j=i-b->len+1;j<i+1;j++) 63 { S2 64 S3 65 S4 66 } 67 S5 68 S6 69 S7 70 } 71 for(;i<a->len+b->len;i++) 72 { carry=0; 73 for(j=i-b->len+1;j<a->len;j++) 74 { S2 75 S3 76 S4 77 } 78 S5 79 S6 80 S7 81 } 82 if(c->val[i-1]!=0) 83 c->len=a->len+b->len; 84 else c->len=a->len+b->len-1; 85 return; 86 } 87 union g {long xx; struct half yy;}; 88 tradd(a,b,c) long c; int *a; union g *b; 89 { 90 b->xx= b->xx+c; 91 if(b->yy.high&0100000) 92 { b->yy.high= b->yy.high&077777; 93 *a += 1; 94 } 95 return; 96 } 97