I have a file into which I want to put a long integer:

00 00 19 7A

The file expects the value in the form:

buffer[0]:=122;
buffer[1]:=25;
buffer[2]:=0;
buffer[3]:=0;

I am then intending to write this buffer to the file

FS.Writebuffer(buffer,4);

Is there a way of loading the buffer directly before writing?

You could use the Absolute directive to map a longint variable to your buffer. Not pretty, but fast ;-)

procedure LoadBuffer;
var
    Buffer: Array[0..127] of Byte;
    l: Longint Absolute Buffer;
begin
    l:= 6522;
end;

Regards, Bernd.

Which file?

buffer[0]:=122; buffer[1]:=25; buffer[2]:=0; buffer[3]:=0;

That's the Intel byte order.

What is "loading"? Reading from the file?

Otherwise buffer can be a variable of any suitable type, e.g. integer.

DoDi

Thanks Bernd.

Won't this mean a different file on big endian and little endian machines?

2009/1/8 Bernd Mueller :

System.Move()

Or you can use pointer operation. Someting like
type
  PLongint = ^Longint;
PLongint(@Buffer[0])^ = 6522;

But be aware: Neither this nor Bernd's way are portable. The order of byte will depend on the architecture your application runs on.

Op donderdag 08-01-2009 om 16:05 uur [tijdzone +0200], schreef Dave Coventry:

var l : longint;
l := NtoBE($197a); // Number to BigEndian
Fs.WriteInt(l);

I don't have tried it, but it must be something like that?

Joost.

Thanks DoDi.

2009/1/8 Hans-Peter Diettrich :

Dave Coventry schrieb: Which file?

It's just a data file that I'm writing to. But it does have to be portable to other applications.

That's the Intel byte order.

Yes, the specification of the datafile require little endian byte order.

What is "loading"? Reading from the file?

No, the integer value is calculated and must be saved to the file. There is more than one integer in a 48 byte block and I want to write this block to the file, so I'm loading a 48 byte buffer. Some of the values are single bytes or text.

It sounds as though the best option is to write my own function:

procedure loadValues(var buffer: Array of Byte; value, startPos,
finPos: integer);
var i: integer;
begin
 for i:=startPos to finPos do
 begin
 buffer[i]:=value and 255;
 value:=value shr 8;
 end;
end;

You can define an according record, and fill in the values there. When the byte order has to be changed, use the according system routines.

DoDi

Must confess, Joost's seemed the most readable, simple and portable :-)

DSP

Duncan Parsons wrote

Must confess, Joost's seemed the most readable, simple and portable :-)

but consider NtoLE, if you are dealing mostly with Little Endian machines. Should be faster then.

Regards, Bernd.

Wouldn't it be a better much nicer way, if something like this were possible:

var l : longintBE;
l := $197a;
Fs.WriteInt(l);

This should just need a new type, operator overloading and an overloaded writeint.

Or adding a new method WriteIntBE is also interesting;

Benito