UM10429
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User manual
Rev. 1 — 20 October 2010
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NXP Semiconductors
UM10429
Chapter 19: Appendix LPC1102 ARM Cortex-M0 reference
19.4.7.4.4
Condition flags
This instruction does not change the flags.
19.4.7.4.5
Examples
DSB ; Data Synchronisation Barrier
19.4.7.5 ISB
Instruction Synchronization Barrier.
19.4.7.5.1
Syntax
ISB
19.4.7.5.2
Operation
ISB acts as an instruction synchronization barrier. It flushes the pipeline of the processor,
so that all instructions following the ISB are fetched from cache or memory again, after the
ISB instruction has been completed.
19.4.7.5.3
Restrictions
There are no restrictions.
19.4.7.5.4
Condition flags
This instruction does not change the flags.
19.4.7.5.5
Examples
ISB
; Instruction Synchronisation Barrier
19.4.7.6 MRS
Move the contents of a special register to a general-purpose register.
19.4.7.6.1
Syntax
MRS
Rd
,
spec_reg
where:
Rd
is the general-purpose destination register.
spec_reg
is one of the special-purpose registers: APSR, IPSR, EPSR, IEPSR, IAPSR,
EAPSR, PSR, MSP, PSP, PRIMASK, or CONTROL.
19.4.7.6.2
Operation
MRS stores the contents of a special-purpose register to a general-purpose register. The
MRS instruction can be combined with the MR instruction to produce read-modify-write
sequences, which are suitable for modifying a specific flag in the PSR.
See
19.4.7.6.3
Restrictions
In this instruction,
Rd
must not be SP or PC.