E2107 Operand size mismatch - delphi

Question

I use this functions since D2007 I got it online, don't remember where.
But now in XE7 it return a compilation error:
"E2107 Operand size mismatch"
function FastCharPos(const aSource : string; const C: Char; StartPos : Integer) : Integer;
var
L : Integer;
begin
//If this assert failed, it is because you passed 0 for StartPos, lowest value is 1 !!
Assert(StartPos > 0);
Result := 0;
L := Length(aSource);
if L = 0 then exit;
if StartPos > L then exit;
Dec(StartPos);
asm
PUSH EDI //Preserve this register
mov EDI, aSource //Point EDI at aSource
add EDI, StartPos
mov ECX, L //Make a note of how many chars to search through
sub ECX, StartPos
mov AL, C //and which char we want :Error -"E2107 Operand size mismatch"
#Loop:
cmp Al, [EDI] //compare it against the SourceString
jz #Found
inc EDI
dec ECX
jnz #Loop
jmp #NotFound
#Found:
sub EDI, aSource //EDI has been incremented, so EDI-OrigAdress = Char pos !
inc EDI
mov Result, EDI
#NotFound:
POP EDI
end;
end;
function FastCharPosNoCase(const aSource : string; C: Char; StartPos : Integer) : Integer;
var
L : Integer;
begin
Result := 0;
L := Length(aSource);
if L = 0 then exit;
if StartPos > L then exit;
Dec(StartPos);
if StartPos < 0 then StartPos := 0;
asm
PUSH EDI //Preserve this register
PUSH EBX
mov EDX, GUpcaseLUT
mov EDI, aSource //Point EDI at aSource
add EDI, StartPos
mov ECX, L //Make a note of how many chars to search through
sub ECX, StartPos
xor EBX, EBX
mov BL, C //:Error -"E2107 Operand size mismatch"
mov AL, [EDX+EBX]
#Loop:
mov BL, [EDI]
inc EDI
cmp Al, [EDX+EBX]
jz #Found
dec ECX
jnz #Loop
jmp #NotFound
#Found:
sub EDI, aSource //EDI has been incremented, so EDI-OrigAdress = Char pos !
mov Result, EDI
#NotFound:
POP EBX
POP EDI
end;
end;
What do I need to update these two functions to XE7 win32?
What must I do?
Thanks.

Answer 1

This code was written for pre Unicode Delphi where Char is an alias for AnsiChar, the 8 bit character type. In Delphi 2009 and later, Char is an alias for WideChar the 16 bit character type.
The reason for the error message is that the code is intended to operate on 8 bit character elements, but you are providing 16 bit operands. The operator expects 8 bit operands, but you supplied 16 bit operands.
Change Char to AnsiChar to make this code compile and behave as intended on all versions of Delphi.
Having said that, I suggest you stop using this code. Instead use Pos. As a rule, it is preferable to use built-in library functions.

Answer 2

You should stop using old assembler version for string routines and use the use built-in library functions.
If you want to move on in a hurry you can reimplement you functions like this:
function FastCharPos(const aSource: string; const C: Char; StartPos: Integer): Integer; inline;
begin
Result := Pos(C, aSource, StartPos);
end;
function FastCharPosNoCase(const aSource: string; C: Char; StartPos: Integer): Integer; inline;
begin
Result := Pos(AnsiUppercase(C), AnsiUppercase(aSource), StartPos);
end;