[fpc-pascal] Byte order modification in fpc on ARM?

[Bo Berglund]

On Mon, 19 Oct 2015 15:32:00 +0200, Jonas Maebe
<jonas.maebe at elis.ugent.be> wrote:

>
>Bo Berglund wrote on Mon, 19 Oct 2015:
>
>> Is there a function or such to interrogate the byte order of the
>> platform FPC runs on? So that I could add a test at the start of
>> download to check if swapping is needed?
>
>Use the http://www.freepascal.org/docs-html/rtl/system/ntobe.html  
>function and you don't have to care about what your host platform uses.
>

This sounds OK were it not for the fact that it has overloaded
implementations for:
Smallint, Word, LongInt, DWord, Int64, QWord.

I need to convert not only integer types but also single precision
floats. These are the main part of the data.

But I have found that I can make an endian test like this:

function PCEndian: boolean;
var
  sTest: string
  fTest: single;
begin
  sTest := #0#0#$20#$40;
  Move(sTest[1], fTest, 4);
  Result := Abs(fTest - 2.5) < 0.01;
end;

Single precision value with hex representation 40200000 is 1.1569E-41
on a PC but 00002040 is exactly 2.5.


-- 
Bo Berglund
Developer in Sweden