Re: [Help-smalltalk] CStruct ABI and packed structs

[Paolo Bonzini]

On 06/07/2010 03:30 AM, Holger Hans Peter Freyther wrote:
>         - Add stdint.h types to cint.h enum and code
>    - Add these to CObject.st

It shouldn't be necessary to add all of stdint.h.  You just need to add 
long long (i.e. hardcoded 64-bit) values.  Then, all values except 
#long/#ulong trivially map to one intXX_t/uintXX_t and you just need to 
cut/paste classes and CDATA_* values.

You can even do this last, since it would only take some 
search-and-replace to change your header file parser

>         - Attempt to add bitfields

This is not hard if you do it entirely in CStruct.  It may require some 
small refactoring, but nothing incredibly difficult.  For the syntax I 
suggest:

    #( ....
       ((#bitfield1  3)
        (#bitfield2  4)
        (#bitfield3  1)) #uint)

since in non-packed structs the type will give you the alignment.

Feel free to add methods like

Integer extend [
    truncateToBits: n [
        "Keep the lowest N bits of the receiver."
        ^self bitAnd: (1 bitShift: n) - 1
    ]

    signExtendToBits: n [
        "Keep the lowest N bits of the receiver and sign extend them
         using two's complement."
        | mask |
        mask := 1 bitShift: n - 1.
        ^(self bitAnd: mask - 1) - (self bitAnd: mask)
    ]
]

>         - Maybe start on the CPP/C Parser and see if what is missing to
>            parse our header files.

The C parser is a bit hard mostly because there is no documentation on 
its state (I found none in 1.1.5).  I think it's simpler to try to whip 
out a simple converter in Perl or awk, like it was done for the GTK+ 
bindings.

Paolo