On Thu, Apr 19, 2018 at 10:32 AM, Thierry Goubier <thierry.goub...@gmail.com > wrote:
> > > 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/ >> > >
