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40 lines
1.4 KiB
ArmAsm
40 lines
1.4 KiB
ArmAsm
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; This is the assembly of:
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;
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; fn is_prime(n: u64) -> bool {
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; (2..n).all(|d| n % d != 0)
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; }
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;
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; Of course, it was compiled in release mode. Thus, this is a primality test
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; which works for numbers >= 2.
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magic:
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push rbp ; standard function prologue:
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mov rbp, rsp ; storing old rbp and setting new one
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mov rcx, rdi ; copy function argument to rcx
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mov esi, 2 ; rsi = 2 (this will be our counter)
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.LBB0_1:
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mov al, 1 ; out = true (rax contains the return value)
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cmp rsi, rcx ; if our counter is equal to our function argument
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jae .LBB0_4 ; (rsi == rcx) we will jump to the end (return)
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xor edx, edx ; set rdx to 0 (just for the upcoming div instruction)
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mov rax, rcx ; copy the function argument into rax temporarily
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; (this is just for the next instruction)
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div rsi ; divide rdx:rax by rsi (counter). The result is stored
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; in rax and more importantly: the remainder is stored
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; in rdx!
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inc rsi ; increment our counter
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test rdx, rdx ; if the remainder is NOT 0, we will jump up
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jne .LBB0_1 ; again (keep going). Else we will just continue...
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xor eax, eax ; out = false
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.LBB0_4:
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pop rbp ; standard function epilogue
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ret
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