Write Dext code for my existing Kext

Hi,I am trying to write Dext code for my existing Kext，How to convert this code to be compatible with Dext？

BufferMemoryDescriptorAME_Module = NULL;
IOMemoryMap *MemMap;

BufferMemoryDescriptorAME_Module= IOBufferMemoryDescriptor::inTaskWithPhysicalMask(kernel_task,kIOMemoryPhysicallyContiguous,otal_memory_size);

BufferMemoryDescriptorAME_Module->prepare(kIODirectionInOut);

MemMap = BufferMemoryDescriptorAME_Module->map(kIOMapInhibitCache);

logicalAddressAME_Module = (UInt8 *) MemMap->getVirtualAddress();

physicalAddressAME_Module = MemMap->getPhysicalAddress();

Thanks, Frederic