Bart schrieb:
On 9/17/13, Mark Morgan Lloyd <[email protected]> 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
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