Passing byte array data from C++ to Haxe

#1

We are trying to pass a raw data from C++ to Haxe, but we had a lot of trebles.

We tried this solution Passing bytes from c++ to haxe but was not working for us.

C++

void Clazz::func(unsigned char *data, int length)
{
    XXX_ENTER_HAXE();
    val_call1(m_callback->get(), alloc_array(length));
    XXX_EXIT_HAXE();
}

Haxe

function func(result:ByteArray) : Void {
    //Do the callback
}

Thanks in advance for any help;

#2

Here’s a couple other approaches

If you know the size in advance, allocate it on the Haxe side, first:

var bytes = Bytes.alloc (length);
make_cffi_call (bytes);

then get the pointer to the data on the C++ side

unsigned char* ptr = (unsigned char*)buffer_data (b);
if (!ptr) ptr = (unsigned char*)val_string (b);

// use ptr to set data

Another approach is to use a Haxe callback to create the array

function allocateBytes (length:Int):Bytes {
    return Bytes.alloc (length);
}

value bytes = val_call1 (m_callback->get(), alloc_int (length));

unsigned char* ptr = (unsigned char*)buffer_data (bytes);
if (!ptr) ptr = (unsigned char*)val_string (bytes);

// use ptr to set data
#3

Hi. Thanks for the quick response.

I’m working on this with hocine also.

Your samples look like they might work for us, but I was wondering, in your example, I don’t see where we plug our bytes into the result.

void CPPClass::sendBytesToHaxe(unsigned char *myBytes, int length)
{
     value haxeBytes = val_call1 (m_callback->get(), alloc_int (length));

     unsigned char* ptr = (unsigned char*)buffer_data (haxeBytes);
     if (!ptr) ptr = (unsigned char*)val_string (haxeBytes);
     
     //Here we want to return myBytes to haxe but
     //how do we transfer myBytes into haxeBytes?
     val_call1(m_myCallback->get(), haxeBytes);
}
#4

If you have Haxe bytes that are allocated with at least the correct size, and get a pointer to where it’s data is stored, you should be able to do something like:

memcpy (ptr, myBytes, length);

…you may also be able to use the Haxe bytes pointer and write to it directly, rather than performing a copy