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

July 6, 2016

      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 <roniesalg@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 <merwanouddane@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 <merwanouddane@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 <roniesalg@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 <merwanouddane@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