factor/vm/generic_arrays.hpp

namespace factor
{

template<typename Array> cell array_capacity(const Array *array)
{
#ifdef FACTOR_DEBUG
	FACTOR_ASSERT(array->type() == Array::type_number);
#endif
	return array->capacity >> TAG_BITS;
}

template<typename Array> cell array_size(cell capacity)
{
	return sizeof(Array) + capacity * Array::element_size;
}

template<typename Array> cell array_size(Array *array)
{
	return array_size<Array>(array_capacity(array));
}

/* Allocates memory */
template<typename Array> Array *factor_vm::allot_uninitialized_array(cell capacity)
{
	Array *array = allot<Array>(array_size<Array>(capacity));
	array->capacity = tag_fixnum(capacity);
	return array;
}

template<typename Array> bool factor_vm::reallot_array_in_place_p(Array *array, cell capacity)
{
	return nursery.contains_p(array) && capacity <= array_capacity(array);
}

/* Allocates memory (sometimes) */
template<typename Array> Array *factor_vm::reallot_array(Array *array_, cell capacity)
{
	data_root<Array> array(array_,this);

	if (array_capacity(array.untagged()) == capacity)
		return array.untagged();

	if(reallot_array_in_place_p(array.untagged(),capacity))
	{
		array->capacity = tag_fixnum(capacity);
		return array.untagged();
	}
	else
	{
		cell to_copy = array_capacity(array.untagged());
		if(capacity < to_copy)
			to_copy = capacity;

		Array *new_array = allot_uninitialized_array<Array>(capacity);

		memcpy(new_array + 1,array.untagged() + 1,to_copy * Array::element_size);
		memset((char *)(new_array + 1) + to_copy * Array::element_size,
		       0,(capacity - to_copy) * Array::element_size);

		return new_array;
	}
}

}