std
Set direction flag
Sets the direction flag (DF), so string instructions step downward through memory.
8086 and later
Used in
- Arrays, strings and the string instructionsx86-64 assembly
CFPFAFZFSFDFOF –––––1–
- 1 always 1
- – not changed
Forms
std
cld clears it, which has to happen before the next call or return: the Linux calling convention expects DF to be clear at both.
global _start
section .text
_start:
mov rax, 12
mov rbx, 5
mov rcx, 3
mov rsi, 9
std
mov rax, 60 ; syscall 60: exit
xor rdi, rdi
syscall