2018-04-19 10:24 GMT+02:00 Serge Stinckwich <serge.stinckw...@gmail.com>:
> > > On Thu, Apr 19, 2018 at 9:13 AM, Serge Stinckwich < > serge.stinckw...@gmail.com> wrote: > >> I try to understand differences between 32 bits and 64 bits FFI support >> for C structures. >> >> I build a class called MyStruct subclass of FFIExternalStructure. >> and define a layout for this structure like this one : >> >> MyStruct class>>fieldsDesc >> "self rebuildFieldAccessors" >> >> ^ #( >> int index ;) >> >> and then I generate automatically the field accessors. >> >> If I use a 32 bit VM, the following method is generated to access the >> index field : >> >> index >> "This method was automatically generated" >> ^handle signedLongAt: OFFSET_INDEX >> >> and if I use a 64 bits VM, the same method is generated ... >> >> I'm a bit puzzled because, if sizeof(int) = sizeof(long) in a 32 bits VM, >> they have different for 64 bits VM (sizeof(int) = 4 and sizeof(long) = 8). >> >> Someone to explain me or this is a bug ? >> >> > Ok I have understood ... > > signedLongAt: method does not return a long as the name seems to indicate > but in fact a 32 bits integer. > So it works in both 32 and 64 bits VM. > > Maybe signedInt32At: would have been a better name :-) > Maybe this is because long in C does not guarantee 64bits, only long long does. Thierry > > > -- > Serge Stinckwich > UMI UMMISCO 209 (SU/IRD/UY1) > "Programs must be written for people to read, and only incidentally for > machines to execute."http://www.doesnotunderstand.org/ >
