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Yes, it took me a bit of thinking to get what was going on in the first place - and the printouts helped me tell that the pointer was walking big steps of 0x190 (400), where you expect to move 20...

Ok, that explains what you are seeing. I'm not quite sure what's wrong with your code, but essentially, you allocate 400 bytes of shared memory (which is correct for 5 * 20 -> 100 int (4 bytes each)...

Can you add a printout of size using %d and tuio_cmd[i] using %p?

Do this on both sides [or you can use gdb to find out the values], and post the results?

--
Mats

I think that's explained in the next post.


My thoughts are that the python is slower than the C code, and you're just getting ahead of the python code.

--
Mats

And what output do you get?

By the way:


tuio_cmd[0]->xo != 0

will always be true for this code:

It's hard to say if you are doing something wrong or not, since we don't see the other half, which I expect it the part that actually fills in the shared memory.

--
Mats

There is also no guarantee that the compiler will re-read lock here:


while (1)
{
if (tuio_cmd[0]->lock)
...