*process source attributes xref or(!);
 /*--------------------------------------------------------------------
 * 13.07.2015 Walter Pachl
 *-------------------------------------------------------------------*/
 minv: Proc Options(main);
 Dcl (x,y) Bin Fixed(31);
 x=42;
 y=2017;
 Put Edit('modular inverse of',x,' by ',y,' ---> ',modinv(x,y))
         (Skip,3(a,f(4)));
 modinv: Proc(a,b) Returns(Bin Fixed(31));
 Dcl (a,b,ob,ox,d,t) Bin Fixed(31);
 ob=b;
 ox=0;
 d=1;

 If b=1 Then;
 Else Do;
   Do While(a>1);
     q=a/b;
     r=mod(a,b);
     a=b;
     b=r;
     t=ox;
     ox=d-q*ox;
     d=t;
     End;
   End;
 If d<0 Then
   d=d+ob;
 Return(d);
 End;
 End;