[fpc-devel] Encoded AnsiString

Hans-Peter Diettrich DrDiettrich1 at aol.com
Sun Dec 29 16:25:46 CET 2013

Michael Van Canneyt schrieb:
> On Sun, 29 Dec 2013, Hans-Peter Diettrich wrote:
>> Inspired by the current Lazarus discussion I'd like to learn more 
>> about the current state of the implementation of the new AnsiStrings.
>> In case nothing has be done yet, I'd suggest to extend TAnsiRec by the 
>> new codePage and elemSize fields (words). These can be zero for now, 
>> so that the remaining codebase is not affected. Then it will be 
>> possible to play around with encoded strings, using the codePage field.
> All this is done already a long time ago in trunk.
> We're way past that stage.

I'm very confused, didn't use FPC for a long time. Have to refresh 
memory of all related procedures...

How do I instruct fpcup to checkout the trunk version? (Windows)
I tried to add an parameter fpcURL=trunk to the shortcut, is this correct?

How do I proceed (build, use in Lazarus...)?
Any links appreciated :-)

> Current stage is the creation of a unicode RTL, where all base 
> file/string operations accept unicode strings. This is done too.
> Next step is creation of the unicode RTL, where "string" = "widestring".
> This will be combined with the dotted unit filenames, to be Delphi 2010+ 
> compatible.

How do I create source files for use with both versions?

> To allow people to choose, 2 RTLs will be created: one unicode 
> (string=ansistring), one non-unicode (string=widestring).
> This will result (probably) in 2 paths:
> units/os-cpu
> units/os-cpu-unicode
> This is not decided yet.
> I planned the work in februari/march.

Thanks :-)

Where can I jump in?

>> A related question:
>> Why is the string length set to zero in NewAnsiString, when the 
>> allocated Length is already known?
> Because the allocated memory length is not necessarily equal to the 
> string length.
> If you have a string of length 50, setting the length to 25 will not 
> discard and reallocate the memory block, but merely set the character 
> length to 25.

This means that the allocated length is stored somewhere else, in the 
memory block descriptor?

How can a user request an string of a specific allocation size?

Another one:

I've heard that a mix of encodings converts the (concatenated) output 
(RawByteString?) to CP_ACP, with possible losses. Is this correct?


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