Re: [Pharo-users] [UFFI] Using a nested structure

[Merwan Ouddane]

PS: for the first example, the alignment is not respected, the vec3 
structure is starting at 9 but uffi is fetching it at 5

On 06/07/2016 17:55, Merwan Ouddane wrote:
Another test:
I replaced double by integer, for visibility...
typedef struct vec3 {
     int data[3];
} vec3;
add a second vec3 to position:

typedef struct position {
     int i;
     vec3 vec;
     vec3 vec2;
} position;

Now in pharo:
Position >> fieldsDesc
"self rebuildFieldAccessors"
    ^ #(
    int i;
    Vec3 vec;
    Vec3 vec2;
)

The size returned for each stucture is 16 instead of 12 that because 
of the "8 byte alignment"

Meaning that the "position" structure is corrupted.

With this function:


extern "C" void DLL_EXPORT fillStruct(position *position)
{
    position -> i = 19;
    (position -> vec).data[0] = 1;
    (position -> vec).data[1] = 2;
    (position -> vec).data[2] = 3;
    (position -> vec2).data[0] = 1;
    (position -> vec2).data[1] = 2;
    (position -> vec2).data[2] = 3;
}

We will get:
position i == 19
position vec at: 1 == 1
position vec2 at: 1 == 2


On Tue, Jul 5, 2016 at 3:12 PM, Ronie Salgado <ronies...@gmail.com 
<mailto:ronies...@gmail.com>> wrote:

    I compiled the DLL using Visual Studio 2015 Community Edition.
    Later I will check with mingw.

    2016-07-05 14:58 GMT+02:00 Merwan Ouddane <merwanoudd...@gmail.com
    <mailto:merwanoudd...@gmail.com>>:

        Using codeblocks, mine are:

        mingw32-g++.exe -m32 -DBUILD_DLL -c main.cpp -o obj\Release\main.o
        mingw32-g++.exe -shared
        -Wl,--output-def=bin\Release\libTest.def
        -Wl,--out-implib=bin\Release\libTest.a -Wl,--dll 
        obj\Release\main.o  -o bin\Release\Test.dll -s -m32


        On Tue, Jul 5, 2016 at 2:52 PM, Merwan Ouddane
        <merwanoudd...@gmail.com <mailto:merwanoudd...@gmail.com>> wrote:

            I am not moving from another plateform :/

            I tried it in pharo 6 and I it didn't work either.

            It could be my dll. What is your compilation line for the
            dll ?

            Thanks you,
            Merwan

            On Tue, Jul 5, 2016 at 2:14 PM, Ronie Salgado
            <ronies...@gmail.com <mailto:ronies...@gmail.com>> wrote:

                Hi Merwan,

                I tested this on Pharo 6 and it is working in Windows.
                However, in 32 bits Window doubles have an 8 byte
                alignment, unlike Linux where they have a 4 byte
                alignment.

                Can you try doing the following before performing the
                ffi call in Windows, if you are moving an image from
                Linux or OS X:

                Vec3 rebuildFieldAccessors.
                Position rebuildFieldAccessors.

                Best regards,
                Ronie

                2016-07-05 11:11 GMT+02:00 Merwan Ouddane
                <merwanoudd...@gmail.com
                <mailto:merwanoudd...@gmail.com>>:

                    Hi,

                    I have an issue whith nested structures.

                    I made some "dummy" structures in c:


                    typedef struct vec3 {
                         double data[3];
                    } vec3;

                    typedef struct position {
                         int i;
                         vec3 vec;
                    } position;

                    And a "dummy" function to fill it:
                    void fillStruct(position *position)
                    {
                        position -> i = 19;
                        (position -> vec).data[0] = 1;
                        (position -> vec).data[1] = 2;
                        (position -> vec).data[2] = 3;
                    }

                    But I can't make the nested structure work.
                    The "i" is correctly set to 19 but I have values
                    that doesn't make any sense in the vec3 structure.

                    In Pharo
                    I declared the Double3 type for the array inside Vec3:
                    Double3 := FFITypeArray ofType: 'double' size: 3

                    Vec3>>fieldsDesc
                        ^ #(
                        Double3 v;
                    )

                    And the position:
                    Position>>fieldsDesc
                        ^ #(
                        int i;
                        Vec3 vec;
                    )

                    The ffi call:
                    ^ self ffiCall: #(void fillStruct(Position
                    *position)) module: 'Test.dll'

                    Sorry for the long / messy mail :p

                    Any clues ?

                    Cheers,
                    Merwan