[Lazarus] Mac (or other BigEndian machine) users needed to test new Utf8StringOfChar code

[Hans-Peter Diettrich]

Bart schrieb:
> On 9/17/13, Mark Morgan Lloyd <markMLl.lazarus at telemetry.co.uk> wrote:
>> Hans-Peter Diettrich wrote:
> 
> HPD code
>     3:
>     begin
>       Result := AUtf8Char;
>       SetLength(Result, nb);
>       PC := PChar(Result);
>       for i:=1 to nb - UCharLen do
>       begin
>         PC[UCharLen] := PC[0];  //very nice b.t.w.
>         inc(PC);
>       end;
>     end;
> 
> My code
> 
>     3:
>     begin
>       SetLength(Result, 3 * N);
>       C1 := AUtf8Char[1];
>       C2 := AUtf8Char[2];
>       C3 := AUtf8Char[3];
>       PC := PChar(Result);
>       for i:=1 to N do
>       begin
>         PC^ := C1; inc(PC);
>         PC^ := C2; inc(PC);
>         PC^ := C3; inc(PC);
>       end;
>     end;
> 
> I tested that for speed, and though they consistently differ about
> 2-6%, on further inspection this is dependant on the order the 2 are
> executed: the first one is always the slower...
> So, I conclude they perform roughly the same.

Thanks for testing :-)

Did you only test the 3-byte case, or also for WORD and DWORD cases? I 
left the "3:" only as a comment to the pattern taken from your code, 
while my version works for any length of the AUTF8Char, not only for the 
3-byte case. It's suited to allow for compiler optimizations, so that 
e.g. REP MOVSB or other streaming instructions could be used for the 
entire loop, as available for a target CPU. This feature makes the 
function usable even for replication of entire strings, of any encoding, 
when the parameter and result type is changed to RawByteString.

DoDi