[fpc-pascal] callback from c with varargs

[Tomas Hajny]

On 2020-12-20 14:00, Jonas Maebe via fpc-pascal wrote:
> On 20/12/2020 13:01, Luca Olivetti via fpc-pascal wrote:
>> El 19/12/20 a les 23:15, Jonas Maebe via fpc-pascal ha escrit:
>>> It is indeed not possible to implement a function with C varargs in 
>>> FPC.
>> 
>> I was afraid that's the answer :-(
>> 
>> as an ugly workaround, I wrote a c library that vsnprintf msg and args
>> to a buffer and then calls a pascal function with no varargs.
>> 
>> It works but, as I said, it's ugly and I'd need to provide a .a for
>> every platform I plan to use.
>> 
>> Is there a better/simpler way (apart from asking the library 
>> developers
>> to use a callback with no varargs)?
> 
> No.

Not necessarily better than platform specific .a files mentioned by 
Luca, but the required playing with stack and registers should be still 
doable with a function written in assembler (inside the Pascal sources), 
shouldn't it?

Tomas