34 lines
1.6 KiB
ArmAsm
34 lines
1.6 KiB
ArmAsm
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.global fib
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.section .text
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fib: push %rbp # Save old rbp to stack and align
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# the stack pointer to 16-bytes.
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movq %rsp, %rbp # Write new base pointer.
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cmpq $1, %rdi # Compare the argument to 1.
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je one # If equal to one go to 'one' and
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# return 1.
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cmpq $0, %rdi # Compare the argument to 0.
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je zero # If equal to zero go to 'zero'
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# and return zero.
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decq %rdi # Decrement n by 1.
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push %rdi # Save the value n - 1 on the stack.
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call fib # Call the function.
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pop %rdi # Restore rdi = n-1
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decq %rdi # Decrement rdi by 1.
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push %rax # Save the result of fib(n-1)
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call fib # Call the function.
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addq (%rsp),%rax # Add the top element (fib(n-1)) to
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# rax which contains fib(n-2).
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jmp end # Jump to 'end' to leave and return
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# from this call to the caller.
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zero: movq $0, %rax # Set return value to 0.
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jmp end
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one: movq $1, %rax # Set return value to 1.
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end: leave # Return the state of the base and
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# stack pointers to their
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# original state.
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ret # Return from the current function
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# with the contents of rax as the
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# return value.
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