Lazarus 64 vs Lazarus 32 on Windows

[Nicola Gorlandi]

Hi all,
I am trying to migrate from Lazarus 32 to Lazarus 64 (both 2.2.4) on Windows.

I have some compiler errors, most of them come from code as below (the error came from l := PCardinal(Cardinal(s) - 4)^; and the error is  Illegal type conversion: "AnsiString" to "LongWord").

By the way, this code is from DIMime library porting from Delphi in Lazarus.

My question is, why on Win32 I do not have such error ?

Many thanks.

Code: Pascal  [Select][+][-]

1. function MimeEncodeString(const s: AnsiString): AnsiString;
2. var
3.   l: Cardinal;
4. begin
5.   if Pointer(s) <> nil then
6.     begin
7.       l := PCardinal(Cardinal(s) - 4)^;
8.       SetString(Result, nil, MimeEncodedSize(l));
9.       MimeEncode(Pointer(s)^, l, Pointer(Result)^);
10.     end
11.   else
12.     Result := '';
13. end;  
14.  

[PascalDragon]

My question is, why on Win32 I do not have such error ?

Cardinal has a size of 4 Byte while a Pointer (and thus also a AnsiString) is 8 Byte on 64-bit systems. Thus these are simply not compatible.

Code: Pascal  [Select][+][-]

1. function MimeEncodeString(const s: AnsiString): AnsiString;
2. var
3.   l: Cardinal;
4. begin
5.   if Pointer(s) <> nil then
6.     begin
7.       l := PCardinal(Cardinal(s) - 4)^;
8.       SetString(Result, nil, MimeEncodedSize(l));
9.       MimeEncode(Pointer(s)^, l, Pointer(Result)^);
10.     end
11.   else
12.     Result := '';
13. end;  
14.  

Why don't you simply use Length(s)? You gain nothing by doing this yourself except potential for errors (also you should declare your size as SizeInt instead of Cardinal, because the type of the length of a string is platform dependant as well).

[ASerge]

An example version, as the comments specified by @PascalDragon

Code: Pascal  [Select][+][-]

1. function MimeEncodeString(const S: AnsiString): AnsiString;
2. var
3.   InputSize, OutputSize: SizeInt;
4. begin
5.   if S <> '' then
6.   begin
7.     InputSize := Length(S);
8.     OutputSize := MimeEncodedSize(InputSize);
9.     SetString(Result, nil, OutputSize);
10.     MimeEncode(Pointer(S)^, InputSize, Pointer(Result)^);
11.   end
12.   else
13.     Result := '';
14. end;

[Nicola Gorlandi]

Many thanks, this solve the issue.

Unfortunately I did not write the procedure, I downloaded somewhere years ago this library in order to code/uncode in base64.

I had already applied your suggestion to another procedure but I am not able to translate this part:
Pointer(Cardinal(Result) + InputSize)^

The function declaration is
function MimeDecodePartialEnd(out OutputBuffer; const ByteBuffer: Cardinal; const ByteBufferSpace: Cardinal): Cardinal;   

I really appreciate your help.

Code: Pascal  [Select][+][-]

1. function MimeDecodeString(const s: AnsiString): AnsiString;
2. var
3.   ByteBuffer, ByteBufferSpace: Cardinal;
4.   l: Cardinal;
5.  
6.  
7.   InputSize, OutputSize: SizeInt;
8.  
9. begin
10.   if S <> '' then
11.     begin
12.       InputSize := Length(S);
13.       SetString(Result, nil, MimeDecodedSize(InputSize));
14.       ByteBuffer := 0;
15.       ByteBufferSpace := 4;
16.       InputSize := MimeDecodePartial(Pointer(s)^, InputSize, Pointer(Result)^, ByteBuffer, ByteBufferSpace);
17.       Inc(InputSize, MimeDecodePartialEnd(Pointer(Cardinal(Result) + InputSize)^, ByteBuffer, ByteBufferSpace));
18.       SetLength(Result, InputSize);
19.     end
20.   else
21.     Result := '';
22. end;  
23.  
24.  

[Nicola Gorlandi]

Sorry I forgot a questiont: is it possible that Lazarus have a library to code / decode in base64 that I can use ?

many thanks again

[howardpc]

Not Lazarus, but FPC.

Code: Pascal  [Select][+][-]

1. uses  base64, ...

[KodeZwerg]

Not Lazarus, but FPC.

Code: Pascal  [Select][+][-]

1. uses  base64, ...

Just for completition
https://www.freepascal.org/docs-html/current/fcl/base64/encodestringbase64.html
https://www.freepascal.org/docs-html/current/fcl/base64/decodestringbase64.html

[PascalDragon]

I had already applied your suggestion to another procedure but I am not able to translate this part:
Pointer(Cardinal(Result) + InputSize)^

Judging by the context you posted I'd use Pointer(@Result[InputSize + 1])^ or - to keep closer to the original code - Pointer(PtrUInt(Result) + InputSize)^.

[Nicola Gorlandi]

Many thanks to everybody, at the end I choose to use the base64 unit in FPC.