OK nevermind I got it now. I talked with Esteban. I had misunderstood. 2016-02-18 14:57 GMT+01:00 Clément Bera <bera.clem...@gmail.com>:
> I don't understand. > > In 32 bits in C, there are 32 bits float called "float" or "single > precision float" but its usage is very uncommon. People always use "double" > as every 32 bits processors supports 64 bits float nowadays. When I look at > the Cairo reference manual, only double are used, so I don't understand why > you need to cast BoxedFloat64 to single precision float for FFI. The > ThreadedIA32FFIPlugin has both #ffiPushDoubleFloat:in: > and ffiPushSingleFloat:in: so all the support seems to be available. > > Can you explain why by default you reduce the precision of float to 32 > bits ? Is it because the library used expects a single precision float to > be passed ? > > > > 2016-02-18 11:57 GMT+01:00 Esteban Lorenzano <esteba...@gmail.com>: > >> but in C (32bits) floats are 4 bytes, so when you do: >> >> ByteArray new >> floatAt: 1 put: somePharoFloat; >> >> it will cast it to 4 bytes (if it fits which is most of the cases). >> >> but as I said… it is an error I need to fix :) >> >> Esteban >> >> >> On 12 Feb 2016, at 20:50, Clément Bera <bera.clem...@gmail.com> wrote: >> >> I don't understand. All BoxedFloat have 8 bytes, that's why they are >> called BoxedFloat64. There are no 4-bytes floats in Pharo. Even in 32 bits. >> >> 2016-02-12 18:06 GMT+01:00 Esteban Lorenzano <esteba...@gmail.com>: >> >>> >>> On 12 Feb 2016, at 17:50, Aliaksei Syrel <alex.sy...@gmail.com> wrote: >>> >>> On Fri, Feb 12, 2016 at 5:45 PM, Esteban Lorenzano <esteba...@gmail.com> >>> wrote: >>> >>>> Float>>#pointer >>>> ^ (ByteArray new: FFIExternalType pointerSize) >>>> floatAt: 1 put: self; >>>> yourself >>>> >>> >>> Yes it does the trick :) Thanks! >>> >>> >>> yes and no (I made a mistake): that works because incidentally pointers >>> and floats have same size (4 bytes)… but can happen that it is not (doubles >>> have 8 bytes)… but is ok for now :) >>> I will fix it correctly next week. >>> >>> Esteban >>> >> >> >> >
