Binary operations.

[Nordlund]

Hi.
I'm too lazy to figure it out by myself.

How do I perform binary operations in D7?

For example (this doesn't work):

function DoSomething(y: longword): longword
begin
  Result := y AND $FF00;    
end;

//Nordlund

 

[whosrdaddy]

???

Did a small test (in D7), worked fine for me..

function DoSomething(y: cardinal): cardinal;
begin
  Result := y AND $FF00;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 showmessage(format('0x%x',[ dosomething($1234)]));
end;

buttonclick shows '0x1200' which is correct...

--------------------------------------
What You See Is What You Get

 

[Nordlund]

Hi.
That's the weird thing.
It !Should! work, but it doesn't....

I solved by using assebler code instead (Code example may not work properly):

function DoSomething(y: cardinal): cardinal;
begin
  asm
    mov eax,y
    and eax,$FF
    mov Result, eax
  end;
end;

//Nordlund

 

[whosrdaddy]

what do you mean by 'it doesnt work' ??
does it give you a bogus result?

have you checked your compiler settings??
...
??

--------------------------------------
What You See Is What You Get

 

[Nordlund]

It gives me the result of 0 every time...

well, it's solved, but thanks anyway...

//Nordlund

 

[towerbase]

Your Assembler code is not the equivalent to your Delphi Pascal code. Is that the cause of the problem?

What values of y did you use and what were the answers?

Which version of Delphi did you use?

Andrew
Hampshire, UK

 

[Nordlund]

OK. Here is the thing.
I'm trying to convert a IP address stored in a LongWord to a IP address splitted in 4 integers.

I tried to mask out the highest 8 bits of the longword, then divide it to get a 0-255 number, and so on...


I might have "reinvented" the wheel by writing own code here

By the way, I'm using Delphi 7...

//Nordlund

 

[Nordlund]

Hi.
When I tried the same example, I got the result I wanted.
It must have been SBK (Shit behind the Keyboard) or less likely, compiler error...


I tried this (exact code) and it didn't work:

  Edit1.Text := FloatToStr(($CA7AB569 AND $FF000000) div $1000000);

Well, this code does the trick too:

procedure DecimalToIP(const IP: LongWord; var IP1, IP2, IP3, IP4: Integer);
begin
  asm
    // IP Highest pair
    mov eax,IP
    shr eax,24
    and eax,$FF
    mov IP1, eax

    // IP "almost" highest pair
    mov eax,IP
    shr eax,16
    and eax,$FF
    mov IP2, eax

    // IP "almost" lowest pair
    mov eax,IP
    shr eax,8
    and eax,$FF
    mov IP3, eax

    // IP lowest pair
    mov eax,IP
    and eax,$FF
    mov IP4, eax
  end;
end;

Sorry for wasting you time guys!

//Nordlund

 

[towerbase]

If you want to avoid assember then you might find this useful:

procedure DecimalToIP(const IP: LongWord; var IP1, IP2, IP3, IP4: Integer);
begin
  ip1 := ( ip and $FF000000 ) shr 24;
  ip2 := ( ip and $00FF0000 ) shr 16;
  ip3 := ( ip and $0000FF00 ) shr 8;
  ip4 := ( ip and $000000FF );
end;

Andrew
Hampshire, UK