FlasCC: interop between Vector.<Number> and double[] - c++

Question

Assume that I am new to AS3 and FlasCC and try to port some legacy C++ code to Flash. What I have is some number-crunching routine that takes an array of type double (the array is of fixed size). The C++ prototype is, say:
double doNumberCrunching(double input[512]);
Now I would like to build an SWC and later call doNumberCrunching() from AS3. SWIG generates the AS3 interface as:
doNumberCrunching(var _input:*):Number;
However, I have no idea how to feed it with Vector.<Number>(512) without working on raw bytes.
My question is: how to solve it neatly? Do you know a cheap way to access double* underlying the Vector.<Number>? Or something even better?

Answer 1

If only your number crunching function was operating on ints! Then you would be able to use CModule.writeIntVector to write vector contents to DomainMemory and just pass over a pointer to the C++ code.
But since it's doubles, you will have to iterate through Vector and convert each element from AS3 Number to C++ double using CModule.writeDouble. Then you can manually expose your function to AS3 with an interface that accepts a DomainMemory pointer:
void doNumberCrunchingAS() __attribute__((used,
annotate("as3sig:public function doNumberCrunching(inputPtr:int):Number"),
annotate("as3package:mypackage"))
));
double doNumberCrunching( double* input )
{
// Actual implementation here
return 0;
}
void doNumberCrunchingAS()
{
// Read the AS3 argument and convert it to a convenient C++ form.
int memoryOffset = 0;
AS3_GetScalarFromVar(memoryOffset, inputPtr);
double* inputPtr = reinterpret_cast<double*>( memoryOffset );
// Call an implementation routine.
double result = doNumberCrunching( inputPtr );
// Return result to AS3 code.
AS3_Return( result );
}
AS3 code:
package
{
using mypackage.doNumberCrunching;
function testNumberCrunching():void
{
var ptr:int = CModule.malloc(blobSize);
// a loop of writeDouble should be here
doNumberCrunching(ptr);
CModule.free(ptr);
}
}