UM10462
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User manual
Rev. 5.5 — 21 December 2016
481 of 523
NXP Semiconductors
UM10462
Chapter 24: LPC11U3x/2x/1x Appendix ARM Cortex-M0
24.4.7.5.3
Restrictions
There are no restrictions.
24.4.7.5.4
Condition flags
This instruction does not change the flags.
24.4.7.5.5
Examples
ISB ; Instruction Synchronisation Barrier
24.4.7.6 MRS
Move the contents of a special register to a general-purpose register.
24.4.7.6.1
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.
24.4.7.6.2
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
24.4.7.6.3
Restrictions
In this instruction,
Rd
must not be SP or PC.
24.4.7.6.4
Condition flags
This instruction does not change the flags.
24.4.7.6.5
Examples
MRS R0, PRIMASK ; Read PRIMASK value and write it to R0
24.4.7.7 MSR
Move the contents of a general-purpose register into the specified special register.
24.4.7.7.1
Syntax
MSR
spec_reg
,
Rn
where:
Rn
is the general-purpose source register.