Bell 32V development

[unix-history] / usr / src / libmp / mult.c

#include <mp.h>
mult(a,b,c) struct mint *a,*b,*c;
{       struct mint x,y,z;
       int sign;
       sign = 1;
       x.val=a->val;
       y.val=b->val;
       z.len=0;
       if(a->len<0)
       {       x.len= -a->len;
               sign= -sign;
       }
       else    x.len=a->len;
       if(b->len<0)
       {       y.len= -b->len;
               sign= -sign;
       }
       else    y.len=b->len;
       if(x.len<y.len) m_mult(&y,&x,&z);
       else m_mult(&x,&y,&z);
       xfree(c);
       if(sign<0) c->len= -z.len;
       else c->len=z.len;
       if(c->len==0) shfree(z.val);
       else c->val=z.val;
       return;
}
#define S2 x=a->val[j];
#define S3 x=x*b->val[i-j];
#define S4 tradd(&carry,&sum,x);
#define S5 c->val[i]=sum.yy.low&077777;
#define S6 sum.xx=sum.xx>>15;
#define S7 sum.yy.high=carry;
m_mult(a,b,c) struct mint *a,*b,*c;
{       long x;
       union {long xx; struct half yy;} sum;
       int carry;
       int i,j;
       c->val=xalloc(a->len+b->len,"m_mult");
       sum.xx=0;
       for(i=0;i<b->len;i++)
       {       carry=0;
               for(j=0;j<i+1;j++)
               {       S2
                       S3
                       S4
               }
               S5
               S6
               S7
       }
       for(;i<a->len;i++)
       {       carry=0;
               for(j=i-b->len+1;j<i+1;j++)
               {       S2
                       S3
                       S4
               }
               S5
               S6
               S7
       }
       for(;i<a->len+b->len;i++)
       {       carry=0;
               for(j=i-b->len+1;j<a->len;j++)
               {       S2
                       S3
                       S4
               }
               S5
               S6
               S7
       }
       if(c->val[i-1]!=0)
               c->len=a->len+b->len;
       else    c->len=a->len+b->len-1;
       return;
}
tradd(a,b,c) long c; int *a; union g {long xx; struct half yy;} *b;
{
       b->xx= b->xx+c;
       if(b->yy.high&0100000)
       {       b->yy.high= b->yy.high&077777;
               *a += 1;
       }
       return;
}