Write a function in assembler that takes a parameter in %rcx and for the low byte, replaces each hex digit D with C. For example, if %rcx = 0x987654321D9 return %rax = 0x987654321C9, if if %rcx = 0x987654321DD return %rax = 0x987654321CC

uint64_t replaceD(uint64_t val);