fizzbuzz.asm

global main
extern puts
extern sprintf
section .text
main:
    push rbx
    mov r15, 100
    mov r14, 1
loop:
    ;print the loop variable into the buffer
    mov rdi, buffer
    mov rsi, format
    mov rdx, r14
    call sprintf

    ;modulo 3 check
    mov rax, r14
    mov rbx, 3
    xor rdx, rdx
    div rbx
    test rdx, rdx
    setz al
    shl al, 1
    mov r8, rax

    ;modulo 5 check
    mov rax, r14
    mov rbx, 5
    xor rdx, rdx
    div rbx
    test rdx, rdx
    setz dl
    or rdx, r8
    
    ;index array of string pointers, and print
    mov rdi, [arr + rdx*8]
    call puts

    ;increment, loop, and return if finished
    inc r14
    cmp r14, r15
    jne loop
    pop rbx
    ret

section .data
format: db "%u", 0 ;format string for sprintf call
buzz: db "Buzz", 0
fizz: db "Fizz", 0
fizzbuzz: db "Fizzbuzz", 0
;array of string pointers for indexing
arr: dq buffer, buzz, fizz, fizzbuzz

section .bss
buffer: resb 3