section .data
fizz_str: db "fizz" ; string for "fizz"
buzz_str: db "buzz" ; string for "buzz"
newline: db 10 ; ascii value for newline
count_to: equ 100 ; count to 100
section .bss
num_buffer: resb 3 ; buffer for number
section .text
global _start
_start:
xor r8, r8 ; initialize counter to 0
main_loop:
inc r8 ; increment counter
xor r9, r9 ; initialize flag to 0
mov rdx, 0 ; clear remainder register
mov rax, r8 ; copy counter to dividend register
mov rcx, 3 ; divisor for fizz
div rcx ; divide by 3
cmp rdx, 0 ; check if remainder is 0
jnz check_buzz ; if not, jump to check_buzz
or r9, 1 ; if yes, set flag to 1
check_buzz:
mov rdx, 0 ; clear remainder register
mov rax, r8 ; copy counter to dividend register
mov rcx, 5 ; divisor for buzz
div rcx ; divide by 5
cmp rdx, 0 ; check if remainder is 0
jnz process_number ; if not, jump to process_number
or r9, 2 ; if yes, set flag to 2
process_number:
cmp r9, 0 ; check if flag is 0
jnz process_fizz ; if not, jump to process_fizz
mov rax, r8 ; copy counter to dividend register
call print_number ; call print_number
jmp check_end ; jump to check_end
process_fizz:
cmp r9, 1 ; check if flag is 1
jnz process_buzz ; if not, jump to process_buzz
call print_fizz ; call print_fizz
jmp check_end ; jump to check_end
process_buzz:
cmp r9, 2 ; check if flag is 2
jnz process_fizzbuzz ; if not, jump to process_fizzbuzz
call print_buzz ; call print_buzz
jmp check_end ; jump to check_end
process_fizzbuzz:
call print_fizzbuzz ; call print_fizzbuzz
check_end:
cmp r8, count_to ; check if counter reached count_to
je exit_program ; if yes, jump to exit_program
jmp main_loop ; if not, jump to main_loop
print_fizzbuzz:
mov rbx, 1 ; set flag to 1 to indicate fizzbuzz
jmp print_fizz ; jump to print_fizz
print_fizz:
xor rbx, rbx ; clear flag
print_fizz_continue:
mov rax, 1 ; syscall number for write
mov rdi, 1 ; file descriptor 1 is stdout
mov rsi, fizz_str ; pointer to fizz_str
mov rdx, 4 ; string length
syscall ; call kernel
cmp r9, 3 ; check if flag is 3 (fizzbuzz)
jne print_newline ; if not, jump to print_newline
jmp print_buzz ; if yes, jump to print_buzz
print_buzz:
mov rax, 1 ; syscall number for write
mov rdi, 1 ; file descriptor 1 is stdout
mov rsi, buzz_str ; pointer to buzz_str
mov rdx, 4 ; string length
syscall ; call kernel
jmp print_newline ; jump to print_newline
print_newline:
mov rax, 1 ; syscall number for write
mov rdi, 1 ; file descriptor 1 is stdout
mov rsi, newline ; pointer to newline
mov rdx, 1 ; string length
syscall ; call kernel
ret ; return from subroutine
print_number:
mov r9, 2 ; set flag to 2
convert_to_ascii:
mov rdx, 0 ; clear remainder register
mov rcx, 10 ; divisor for conversion
div rcx ; divide
add rdx, 0x30 ; convert to ASCII
mov [num_buffer+r9], dl ; store in buffer
dec r9 ; decrement flag
cmp rax, 0 ; check if dividend is 0
jnz convert_to_ascii ; if not, jump to convert_to_ascii
mov rax, 1 ; syscall number for write
mov rdi, 1 ; file descriptor 1 is stdout
mov rsi, num_buffer ; pointer to num_buffer
mov rdx, 3 ; string length
syscall ; call kernel
call print_newline ; call print_newline
ret ; return from subroutine
exit_program:
mov rax, 60 ; syscall number for exit
xor rdi, rdi ; exit code 0
syscall ; call kernel
Write, Run & Share Assembly code online using OneCompiler's Assembly online compiler for free. It's one of the robust, feature-rich online compilers for Assembly language. Getting started with the OneCompiler's Assembly compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as Assembly and start coding.
Assembly language(asm) is a low-level programming language, where the language instructions will be more similar to machine code instructions.
Every assembler may have it's own assembly language designed for a specific computers or an operating system.
Assembly language requires less execution time and memory. It is more helful for direct hardware manipulation, real-time critical applications. It is used in device drivers, low-level embedded systems etc.
Assembly language usually consists of three sections,
Data section
To initialize variables and constants, buffer size these values doesn't change at runtime.
bss section
To declare variables
text section
_start specifies the starting of this section where the actually code is written.
There are various define directives to allocate space for variables for both initialized and uninitialized data.
variable-name define-directive initial-value
| Define Directive | Description | Allocated Space |
|---|---|---|
| DB | Define Byte | 1 byte |
| DW | Define Word | 2 bytes |
| DD | Define Doubleword | 4 bytes |
| DQ | Define Quadword | 8 bytes |
| DT | Define Ten Bytes | 10 bytes |
| Define Directive | Description |
|---|---|
| RESB | Reserve a Byte |
| RESW | Reserve a Word |
| RESD | Reserve a Doubleword |
| RESQ | Reserve a Quadword |
| REST | Reserve a Ten Bytes |
Constants can be defined using
CONSTANT_NAME EQU regular-exp or value
%assign constant_name value
%define constant_name value
Loops are used to iterate a set of statements for a specific number of times.
mov ECX,n
L1:
;<loop body>
loop L1
where n specifies the no of times loops should iterate.
Procedure is a sub-routine which contains set of statements. Usually procedures are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
procedure_name:
;procedure body
ret