2.9BSD - /usr/src/lib/mp/mult.c

   1: /*	@(#)mult.c	4.1	12/25/82	*/
   2: 
   3: #include <mp.h>
   4: mult(a,b,c) struct mint *a,*b,*c;
   5: {   struct mint x,y,z;
   6:     int sign;
   7:     sign = 1;
   8:     x.val=a->val;
   9:     y.val=b->val;
  10:     z.len=0;
  11:     if(a->len<0)
  12:     {   x.len= -a->len;
  13:         sign= -sign;
  14:     }
  15:     else    x.len=a->len;
  16:     if(b->len<0)
  17:     {   y.len= -b->len;
  18:         sign= -sign;
  19:     }
  20:     else    y.len=b->len;
  21:     if(x.len<y.len) m_mult(&y,&x,&z);
  22:     else m_mult(&x,&y,&z);
  23:     xfree(c);
  24:     if(sign<0) c->len= -z.len;
  25:     else c->len=z.len;
  26:     if(c->len==0) shfree(z.val);
  27:     else c->val=z.val;
  28:     return;
  29: }
  30: #define S2 x=a->val[j];
  31: #define S3 x=x*b->val[i-j];
  32: #define S4 tradd(&carry,&sum,x);
  33: #define S5 c->val[i]=sum.yy.low&077777;
  34: #define S6 sum.xx=sum.xx>>15;
  35: #define S7 sum.yy.high=carry;
  36: m_mult(a,b,c) struct mint *a,*b,*c;
  37: {   long x;
  38:     union {long xx; struct half yy;} sum;
  39:     int carry;
  40:     int i,j;
  41:     c->val=xalloc(a->len+b->len,"m_mult");
  42:     sum.xx=0;
  43:     for(i=0;i<b->len;i++)
  44:     {   carry=0;
  45:         for(j=0;j<i+1;j++)
  46:         {   S2
  47:             S3
  48:             S4
  49:         }
  50:         S5
  51:         S6
  52:         S7
  53:     }
  54:     for(;i<a->len;i++)
  55:     {   carry=0;
  56:         for(j=i-b->len+1;j<i+1;j++)
  57:         {   S2
  58:             S3
  59:             S4
  60:         }
  61:         S5
  62:         S6
  63:         S7
  64:     }
  65:     for(;i<a->len+b->len;i++)
  66:     {   carry=0;
  67:         for(j=i-b->len+1;j<a->len;j++)
  68:         {   S2
  69:             S3
  70:             S4
  71:         }
  72:         S5
  73:         S6
  74:         S7
  75:     }
  76:     if(c->val[i-1]!=0)
  77:         c->len=a->len+b->len;
  78:     else    c->len=a->len+b->len-1;
  79:     return;
  80: }
  81: tradd(a,b,c) long c; int *a; union g {long xx; struct half yy;} *b;
  82: {
  83:     b->xx= b->xx+c;
  84:     if(b->yy.high&0100000)
  85:     {   b->yy.high= b->yy.high&077777;
  86:         *a += 1;
  87:     }
  88:     return;
  89: }

Defined functions

Defined union's

Defined macros