Hi Tony,
On 11.01.2016 17:56, Tony Cappellini wrote:
>
>
> I've already got a project built for Linux, using Boost-python. My
> Python code can import the C++ extension and access the members that
> are exposed.
>
> My C++ code needs to call fill in C++ structures in order to call
> ioctl() functions, while passing the addresses of the structures to
> the ioctl functions.
>
> I also need to allocate large (10's of MB - 100s of MB) buffers which
> must be aligned to specific boundaries. A pointer to these buffers are
> part of the above-mentioned C++ structs.
> (I already have the C++ functions which handle the alignment and
> memory allocation)
>
> The problems I'm facing are:
> 1. How to initiate the memory allocation from Python, so that the
> user has access to the
> data after the ioctl() completes. This would eliminate the
> need from copying the data from
> C++ to Python, after each ioctl() call.
> 2. Using boost-python, which type of Python data structure is
> best suited to be shared across
> the C++/Python boundary? Keep in mind that the allocation
> needs to happen in C++ so that
> memory alignment can be maintained, but initiating the
> allocation/alignment will be done from
> Python.
What you are describing all sounds quite feasible.
>
> Essentially- Python needs access to the return value from a malloc() call.
Really ? Why ? You say your C++ code needs to access the pointer(s).
Python has no notion of "pointer", but it will happily pass around
whatever data you expose from C++.
So let's say you have a C++ class (or struct if you prefer) that
encapsulates the data and methods, such as:
class something
{
public:
something() : buffer_(allocate_memory()) {}
void call_ioctl() { /*...*/}
private:
char *buffer_;
};
if you expose the above class together with the constructor and the
'call_ioctl()' member function I think you have all you need.
If not, please elaborate.
Stefan
--
...ich hab' noch einen Koffer in Berlin...
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