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Im making a very simple and basic assembly program (create array with 0 to 15, find the prime numbers, square each number and do the fibonacci in each). But everytime i run it i get a a segmentation fault (SIGSEGV), exit code: -11. No AIs could find out why, not even claude i guess they aint that trainded on assembly yet. Im using NASM 2.15.05 (on Linux x86_64). Can u help me please i would really appreciate it!!
section .data
array_int db 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
section .bss ; alocar espaços vazios de memoria
primos resb 16
potencias resw 16
fib_results resw 16 ; serão usados registradores de 16 bits para fibonacci
section .text
global _start
e_primo:
cmp al, 2
jl nao_primo ; menor que 2 não é primo
je sim_primo ; 2 é primo
test al, 1 ; AND entre bits menos significat. Pares sempre comecam com 0. Pares não são primos
jz nao_primo
mov cl, 3 ; após inicializar primeiro divisor, "JUMP" pra checa_div
checa_div:
mov bl, al ;
mov al, cl ; porque o AL é um registrador q tem q ser usado em MUL
mul al ; AL por ele mesmo
cmp al, bl ; checa se ja passou da sqrt do num: todos necessarios ja foram checados
jg sim_primo
mov al, bl
mov ah, 0 ; zera registrador q armazena resto
div cl
cmp ah, 0
je nao_primo
add cl, 2 ; queremos checar apenas impares
mov al, bl ; valor em AL é alterado na divisao
jmp checa_div
nao_primo:
mov al, 0
ret
sim_primo:
mov al, 1
ret
start_fibo:
mov dx, 0
cmp al, 0
je end_fibo
mov dx, 1
cmp al, 1
je end_fibo ; fibo 0 e 1 é eles mesmos
mov bx, 0
mov dx, 1
mov cx, ax ; cx é usado no loop (AX vezes)
sub cx, 1 ; primeiro ja tratado
fib_loop:
mov ax, dx ; salva f(n) em ax
add dx, bx ; dx = f(n) + f(n - 1) = f(n + 1)
mov bx, ax ; f(n)
loop fib_loop
end_fibo:
mov ax, dx
ret
_start:
lea rsi, [array_int]
lea rdi, [primos]
lea rdx, [potencias]
lea r15, [fib_results]
mov rcx, 16
loop_array:
mov al, [rsi]
call e_primo
mov[rdi], al
movzx ax, byte [rsi] ; restaura AL (registrador de 16 agora)
mul al ; potencia do valor em AL
mov [rdx], ax
movzx ax, byte [rsi]
call start_fibo
mov [r15], ax
inc rsi
inc rdi
add rdx, 2
add r15, 2
loop loop_array
mov rax, 60
xor rdi, rdi
syscall
idk i tried a lot of things
Im making a very simple and basic assembly program (create array with 0 to 15, find the prime numbers, square each number and do the fibonacci in each). But everytime i run it i get a a segmentation fault (SIGSEGV), exit code: -11. No AIs could find out why, not even claude i guess they aint that trainded on assembly yet. Im using NASM 2.15.05 (on Linux x86_64). Can u help me please i would really appreciate it!!
section .data
array_int db 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
section .bss ; alocar espaços vazios de memoria
primos resb 16
potencias resw 16
fib_results resw 16 ; serão usados registradores de 16 bits para fibonacci
section .text
global _start
e_primo:
cmp al, 2
jl nao_primo ; menor que 2 não é primo
je sim_primo ; 2 é primo
test al, 1 ; AND entre bits menos significat. Pares sempre comecam com 0. Pares não são primos
jz nao_primo
mov cl, 3 ; após inicializar primeiro divisor, "JUMP" pra checa_div
checa_div:
mov bl, al ;
mov al, cl ; porque o AL é um registrador q tem q ser usado em MUL
mul al ; AL por ele mesmo
cmp al, bl ; checa se ja passou da sqrt do num: todos necessarios ja foram checados
jg sim_primo
mov al, bl
mov ah, 0 ; zera registrador q armazena resto
div cl
cmp ah, 0
je nao_primo
add cl, 2 ; queremos checar apenas impares
mov al, bl ; valor em AL é alterado na divisao
jmp checa_div
nao_primo:
mov al, 0
ret
sim_primo:
mov al, 1
ret
start_fibo:
mov dx, 0
cmp al, 0
je end_fibo
mov dx, 1
cmp al, 1
je end_fibo ; fibo 0 e 1 é eles mesmos
mov bx, 0
mov dx, 1
mov cx, ax ; cx é usado no loop (AX vezes)
sub cx, 1 ; primeiro ja tratado
fib_loop:
mov ax, dx ; salva f(n) em ax
add dx, bx ; dx = f(n) + f(n - 1) = f(n + 1)
mov bx, ax ; f(n)
loop fib_loop
end_fibo:
mov ax, dx
ret
_start:
lea rsi, [array_int]
lea rdi, [primos]
lea rdx, [potencias]
lea r15, [fib_results]
mov rcx, 16
loop_array:
mov al, [rsi]
call e_primo
mov[rdi], al
movzx ax, byte [rsi] ; restaura AL (registrador de 16 agora)
mul al ; potencia do valor em AL
mov [rdx], ax
movzx ax, byte [rsi]
call start_fibo
mov [r15], ax
inc rsi
inc rdi
add rdx, 2
add r15, 2
loop loop_array
mov rax, 60
xor rdi, rdi
syscall
idk i tried a lot of things
Share Improve this question asked Mar 16 at 23:00 big_dddddd_boybig_dddddd_boy 111 silver badge2 bronze badges 1- 2 Have you stepped through this with a debugger? That should quickly identify where the fault is. – Tangentially Perpendicular Commented Mar 16 at 23:02
1 Answer
Reset to default 1Please read Assembly registers in 64-bit architecture
- e_primo is allowed to change the CL register that is part of the RCX register that controls your main loop.
- start_fibo is allowed to change the CX register that is part of the RCX register that controls your main loop, as well as the DX register that is part of the RDX register that addresses the potencias array.
With these disruptive clobbers, rather sooner than later will the program try to address memory outside of .data or .bss and hence your segmentation fault.
A solution is to preserve some registers (on the stack) before calling e_primo and start_fibo from within your main loop.
loop_array:
push rcx
mov al, [rsi]
call e_primo
...
push rdx
call start_fibo
pop rdx
...
pop rcx
loop loop_array
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