The BaseTools/Scripts/ConvertMasmToNasm.py script was used to convert X64/EbcLowLevel.asm to X64/EbcLowLevel.nasm And, manually update nasm code to use mov rcx, dword value and generate the same assembly code with rcx register to asm code. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>