[Vm-dev] [Cuis-dev] Support for LP64 & LLP64 in FFI Kernel

[Juan Vuletich]

On 19/01/2017 02:53 p.m., Eliot Miranda via Cuis-dev wrote:
> Hi All,
>
>     currently the FFI has support for 8, 16, 32 & 64 bit integers, but 
> no support for C's long type.  In almost all C implementations byte is 
> 8 bits, short is 16 bits, int is 32 bits and long long is 64 bits.  
> But long may be either 32 or 64 bits depending on programming model.
>
> In LP32 long is 32 bits, which is used in 32-bit unix, mac os and windows.
> In LP64 long is 64 bits, which is used in 64-bit unix and mac os.
> In LLP64 long is 32 bits, which is used in 64-bit windows.
>
> So having a type which is either 32 or 64 bits depending on platform 
> is useful in modeling C's long type across platforms.  Esteban and I 
> propose adding such a type to FFI kernel, actually two types, one 
> unsigned, one signed.  So we propose extending the below (these 
> constants are used to define signatures for FFI calls and the contents 
> of structs)
>
> FFIConstants class>>#initializeTypeConstants
> "type void"
> FFITypeVoid := 0.
>
> "type bool"
> FFITypeBool := 1.
>
> "basic integer types.
> note: (integerType anyMask: 1) = integerType isSigned"
>
> FFITypeUnsignedByte := 2.
> FFITypeSignedByte := 3.
> FFITypeUnsignedShort := 4.
> FFITypeSignedShort := 5.
> FFITypeUnsignedInt := 6.
> FFITypeSignedInt := 7.
>
> "64bit types"
> FFITypeUnsignedLongLong := 8.
> FFITypeSignedLongLong := 9.
>
> "special integer types"
> FFITypeUnsignedChar := 10.
> FFITypeSignedChar := 11.
>
> "float types"
> FFITypeSingleFloat := 12.
> FFITypeDoubleFloat := 13.
>
> "type flags"
> FFIFlagAtomic := 16r40000. "type is atomic"
> FFIFlagPointer := 16r20000. "type is pointer to base type"
> FFIFlagStructure := 16r10000. "baseType is structure of 64k length"
> FFIStructSizeMask := 16rFFFF. "mask for max size of structure"
> FFIAtomicTypeMask := 16r0F000000. "mask for atomic type spec"
> FFIAtomicTypeShift := 24. "shift for atomic type"
>
> to add to
> "special integer types"
> FFITypeUnsignedChar := 10.
> FFITypeSignedChar := 11.
> FFITypePlatformUnsignedLong := 14.
> FFITypePlatformSignedLong := 15.
>
> This is backward compatible, even if it complicates the marshaling a 
> little since it used to be that all integer types were less than 
> FFITypeSingleFloat.  But breaking backward compatibility would be a 
> bad idea.
>
> Then in ByteArray et al we could add accessors for platformLongAt: 
> platformUnsignedLongAt:.
>
> Comments, thoughts, objections?
> _,,,^..^,,,_
> best, Eliot
>

Looks great to me.

Thanks,

-- 
Juan Vuletich
www.cuis-smalltalk.org
https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev
@JuanVuletich

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.squeakfoundation.org/pipermail/vm-dev/attachments/20170122/d63d280c/attachment.html>