4.3BSD - /usr/src/usr.lib/libmp/madd.c

   1: /*
   2:  * Copyright (c) 1980 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifndef lint
   8: static char sccsid[] = "@(#)madd.c	5.1 (Berkeley) 4/30/85";
   9: #endif not lint
  10: 
  11: #include <mp.h>
  12: m_add(a,b,c) struct mint *a,*b,*c;
  13: {   int carry,i;
  14:     int x;
  15:     short *cval;
  16:     cval=xalloc(a->len+1,"m_add");
  17:     carry=0;
  18:     for(i=0;i<b->len;i++)
  19:     {   x=carry+a->val[i]+b->val[i];
  20:         if(x&0100000)
  21:         {   carry=1;
  22:             cval[i]=x&077777;
  23:         }
  24:         else
  25:         {   carry=0;
  26:             cval[i]=x;
  27:         }
  28:     }
  29:     for(;i<a->len;i++)
  30:     {   x=carry+a->val[i];
  31:         if(x&0100000) cval[i]=x&077777;
  32:         else
  33:         {   carry=0;
  34:             cval[i]=x;
  35:         }
  36: 
  37:     }
  38:     if(carry==1)
  39:     {   cval[i]=1;
  40:         c->len=i+1;
  41:     }
  42:     else c->len=a->len;
  43:     c->val=cval;
  44:     if(c->len==0) shfree(cval);
  45:     return;
  46: }
  47: madd(a,b,c) struct mint *a,*b,*c;
  48: {   struct mint x,y,z;
  49:     int sign;
  50:     x.len=a->len;
  51:     x.val=a->val;
  52:     y.len=b->len;
  53:     y.val=b->val;
  54:     z.len=0;
  55:     sign=1;
  56:     if(x.len>=0)
  57:         if(y.len>=0)
  58:             if(x.len>=y.len) m_add(&x,&y,&z);
  59:             else m_add(&y,&x,&z);
  60:         else
  61:         {   y.len= -y.len;
  62:             msub(&x,&y,&z);
  63:         }
  64:     else    if(y.len<=0)
  65:         {   x.len = -x.len;
  66:             y.len= -y.len;
  67:             sign= -1;
  68:             madd(&x,&y,&z);
  69:         }
  70:         else
  71:         {   x.len= -x.len;
  72:             msub(&y,&x,&z);
  73:         }
  74:      xfree(c);
  75:     c->val=z.val;
  76:     c->len=sign*z.len;
  77:     return;
  78: }
  79: m_sub(a,b,c) struct mint *a,*b,*c;
  80: {   int x,i;
  81:     int borrow;
  82:     short one;
  83:     struct mint mone;
  84:     one=1; mone.len= 1; mone.val= &one;
  85:     c->val=xalloc(a->len,"m_sub");
  86:     borrow=0;
  87:     for(i=0;i<b->len;i++)
  88:     {   x=borrow+a->val[i]-b->val[i];
  89:         if(x&0100000)
  90:         {   borrow= -1;
  91:             c->val[i]=x&077777;
  92:         }
  93:         else
  94:         {   borrow=0;
  95:             c->val[i]=x;
  96:         }
  97:     }
  98:     for(;i<a->len;i++)
  99:     {   x=borrow+a->val[i];
 100:         if(x&0100000) c->val[i]=x&077777;
 101:         else
 102:         {   borrow=0;
 103:             c->val[i]=x;
 104:         }
 105:     }
 106:     if(borrow<0)
 107:     {   for(i=0;i<a->len;i++) c->val[i] ^= 077777;
 108:         c->len=a->len;
 109:         madd(c,&mone,c);
 110:     }
 111:     for(i=a->len-1;i>=0;--i) if(c->val[i]>0)
 112:                 {   if(borrow==0) c->len=i+1;
 113:                     else c->len= -i-1;
 114:                     return;
 115:                 }
 116:     shfree(c->val);
 117:     return;
 118: }
 119: msub(a,b,c) struct mint *a,*b,*c;
 120: {   struct mint x,y,z;
 121:     int sign;
 122:     x.len=a->len;
 123:     y.len=b->len;
 124:     x.val=a->val;
 125:     y.val=b->val;
 126:     z.len=0;
 127:     sign=1;
 128:     if(x.len>=0)
 129:         if(y.len>=0)
 130:             if(x.len>=y.len) m_sub(&x,&y,&z);
 131:             else
 132:             {   sign= -1;
 133:                 msub(&y,&x,&z);
 134:             }
 135:         else
 136:         {   y.len= -y.len;
 137:             madd(&x,&y,&z);
 138:         }
 139:     else    if(y.len<=0)
 140:         {   sign= -1;
 141:             x.len= -x.len;
 142:             y.len= -y.len;
 143:             msub(&y,&x,&z);
 144:         }
 145:         else
 146:         {   x.len= -x.len;
 147:             madd(&x,&y,&z);
 148:             sign= -1;
 149:         }
 150:     if(a==c && x.len!=0) xfree(a);
 151:     else if(b==c && y.len!=0) xfree(b);
 152:     else xfree(c);
 153:     c->val=z.val;
 154:     c->len=sign*z.len;
 155:     return;
 156: }

Defined functions

Defined variables