I was thinking about how to return error info in FASMLIB. Originally i was thinking about some static structure in memory, but then friend found out that this can't be used with multi-threaded apps.

Right now, the error status is always(!) returned in CF, and if error occurs, then nothing else is returned.

One idea is to return address of error structure in EAX, this seems nice, but problem arises - how to allocate memory? In future i plan to implement automatic callstack to become part of error info (in debugging versions), so it cannot be just some small chunk of memory.

Second idea is to rely on system memory allocation, and if it fails then return some kind of "Error info couldn't be generated" instead of description / call stack / anything

anyone has better ideas?

PS: maybe even other register could be used, so you can change it in handler, but which? this is just an idea, i personally dislike it.

Why not use TLS?

If I remember well the TLS slot for the EXE module is 0 so doing "mov dword [fs:0], something" should be enough. For DLLs you should use the API function to get a slot.

Regards

you could set the CF to 1 and do something like this:


then you return from the procedure and that is, you should have the memory address of the message and even you can use something like putting on ah the memory address and in al some error number.

Bye

Thaorious - that's way i use already, but i also need some strings created dynamically (like "Error in procedure %s: arg1 = %8X, arg2 = %8X" etc...), so i need memory for this

what's that TLS? i am not familiar with it

TLS is only in PE files. FASMLIB is supposed to be OS-independent, and so error handling must be the same on all OSes.

it is possible with additional optional parameter. if caller wish to get error info - it allocates space for error structure and pass pointer as parameter to the function (it has to be able to fill it) - if there is no error - it simply deleted, otherwise - used (filled by called function, of course). if caller do not care about error - 0 passed as this parameter. that structure can be created even in stack as local var, so, no problems with multythreading.

You have Thread Local Store (TLS) on Windows and Thread Specific Data (TSD) on Linux. Again if I remember well on Linux you can use "mov [fs:0], something" but I'd never used it on Linux so you must Google it.

Absolutelly wrong.


http://www.microsoft.com/msj/0298/hood0298.aspx

[fs:0] is the head of the exception handling linked list.
If you want more info, contact me.

There was a big mess yesterday for that http://board.flatassembler.net/topic.php?t=5807

Thanks anyway.