global My_isupper ; this function takes one parameter, so that will be in rdi ; it returns one value, in rax ; 0 if rdi contains a non-upper case letter ; 1 if rdi contains an upper case letter My_isupper: ; if (rsi < 'A') return false cmp dil, 41h jl not ; if (rsi > 'Z') return false cmp dil, 5Ah jg not ; return true mov rax, 1 jmp done not: mov rax, 0 done: ret