Twos Complement

[gehakte_bits]

This might help, it follows mostly the traditional 2sC methods around..
(added save Signed state for those that use Signed, and crop to the requested bit width.)

Code:


// 2023.0218 pretty-prime v0.3b
#pragma mode(separator(.,;) integer(h32))

// cmpl_2(#FBh,8) -> -5
// cmpl_2(#FFFBh,8) -> -5
// cmpl_2(#FBh,16) -> 251
// cmpl_2(-5,16) -> #FFFBh
// cmpl_2(5,16) -> #5h

//===============
// 2's Complement
//===============
EXPORT cmpl_2(x,m)
BEGIN
LOCAL s:=Signed;
  Signed:=0; 
  CASE 

    IF TYPE(x)=0 THEN                       // real to integer
      x:=IP(x);
      IF -2^(m-1)≤x<2^(m-1) THEN            // range check integer m sized
        x:=SETBITS(R→B(x,m));
      ELSE 
        x:=0;
      END;
    END;

    IF TYPE(x)=1 THEN                       // integer to real
      IF BITAND(x,2^(m-1)) THEN             // test msb bit neg flag
        x:=-1*(1+BITNOT(SETBITS(x,m-1)));   // (invert m-bits)+1 to real
      ELSE 
         x:=B→R(SETBITS(x,m));
      END;
    END;

  END;
  Signed:=s;
  RETURN x;
END;