rol
Rotate left
Rotates the destination (first) operand left by the given count, moving bits that leave the top back in at the bottom.
8086 and later
CFPFAFZFSFDFOF ●–––––?
- ● set from the result
- ? undefined afterwards
- – not changed
- OF Defined only for a count of 1.
- A count of 0 leaves every flag unchanged.
Forms
Operands
r/m- A general-purpose register or memory location matching the operation’s size, for example
raxorqword [rbp-8]. The byte registersah,bh,chanddhcannot be used with a REX prefix, including when the memory address usesr8–r15. imm8- An 8-bit immediate,
-128to255. Instructions that sign-extend it to a wider operand interpret the byte as-128to127; shift counts do not use this sign extension.
CF receives the last bit rotated out, and OF is defined only for a count of one.
The count comes from an immediate or cl. It is first masked to six bits for a 64-bit operand or five bits for smaller operands, then reduced modulo the operand width for the rotation. A 64-bit rotation by 32 therefore exchanges the two 32-bit halves; a count of 64 masks to zero.
global _start
section .text
_start:
mov rax, 12
mov rbx, 5
mov rcx, 3
mov rsi, 9
rol rax, 1
mov rax, 60 ; syscall 60: exit
xor rdi, rdi
syscall