fib.s

        .section        .rodata

.LC0:
        .string "%lli\n"

        .text

        .type   print, @function
print:
        PUSH    %rdi
        PUSH    %rsi
        MOV     %rdi, %rsi
        LEA     .LC0(%rip), %rdi
        CALL    printf
        POP     %rsi
        POP     %rdi
        RET
        .size   print, . - print

        .globl  fib
        .type   fib, @function
fib:
        MOV     $2, %rbx
        CMP     %rbx, %rdi
        SETL    %al
        MOVZX   %al, %rbx
        TEST    %rbx, %rbx
        JZ      .L0
        MOV     %rdi, %rax
        RET
        JMP     .L1
.L0:
        MOV     $1, %rbx
        MOV     %rdi, %rbp
        SUB     %rbx, %rbp
        PUSH    %rdi
        MOV     %rbp, %rdi
        XOR     %rax, %rax
        CALL    fib
        POP     %rdi
        PUSH    %rax
        MOV     $2, %rbx
        MOV     %rdi, %rbp
        SUB     %rbx, %rbp
        PUSH    %rdi
        MOV     %rbp, %rdi
        XOR     %rax, %rax
        CALL    fib
        POP     %rdi
        MOV     %rax, %rbx
        POP     %rax
        ADD     %rax, %rbx
        MOV     %rbx, %rax
        RET
.L1:
        RET
        .size   fib, . - fib

        .globl  iter
        .type   iter, @function
iter:
        CMP     %rsi, %rdi
        SETE    %al
        MOVZX   %al, %rbx
        TEST    %rbx, %rbx
        JZ      .L2
        XOR     %rbx, %rbx
        MOV     %rbx, %rax
        RET
        JMP     .L3
.L2:
        PUSH    %rdi
        XOR     %rax, %rax
        CALL    fib
        POP     %rdi
        PUSH    %rdi
        MOV     %rax, %rdi
        XOR     %rax, %rax
        CALL    print
        POP     %rdi
        MOV     $1, %rbx
        ADD     %rdi, %rbx
        PUSH    %rdi
        MOV     %rbx, %rdi
        PUSH    %rsi
        XOR     %rax, %rax
        CALL    iter
        POP     %rsi
        POP     %rdi
        RET
.L3:
        RET
        .size   iter, . - iter

        .globl  main
        .type   main, @function
main:
        XOR     %rbx, %rbx
        PUSH    %rdi
        MOV     %rbx, %rdi
        MOV     $50, %rbx
        PUSH    %rsi
        MOV     %rbx, %rsi
        XOR     %rax, %rax
        CALL    iter
        POP     %rsi
        POP     %rdi
        RET
        .size   main, . - main