isb

Instruction Synchronization Barrier (Thumb)

ISB <option>

Instruction barrier (Thumb).

Pseudocode Operation

if option == SY then
  InstructionSynchronizationBarrier()
else
  InstructionSynchronizationBarrier()

Example

ISB option

Encoding

Binary Layout

111100111011

31:20

1

19

1

18

1

17

1

16

10

15:14

0

13

0

12

1

11

1

10

1

9

1

8

0110

7:4

option

3:0

 

Format Thumb System

Opcode 0xF3BF8F60

Extension A32 (Base)

Operands

• option
  SY

Related

Other forms of isb

• isb Instruction Synchronization Barrier
• isb Instruction Synchronization Barrier (A32)

More in A32 (Base)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xF57FF060	ISB{<c>}{<q>} {<option>}		A32		111101010111 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0110 | option
0xF3BF8F60	ISB{<c>}{<q>} {<option>}		T32		111100111011 | 1 | 1 | 1 | 1 | 10 | 0 | 0 | 1 | 1 | 1 | 1 | 0110 | option

Description

Instruction Synchronization Barrier flushes the pipeline in the PE and is a context synchronization event. For more information, see Instruction Synchronization Barrier (ISB).

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    InstructionSynchronizationBarrier();