ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Assembler syntax
MRS ,
where:
See Standard assembler syntax fields on page A8-7.
The destination register.
Is one of:
Operation
System Instructions
• APSR
• CPSR
• SPSR.
ARM recommends the APSR form when only the N, Z, C, V, Q, or GE[3:0] bits of the read
value are going to be used (see The Application Program Status Register (APSR) on
page A2-14).
if ConditionPassed() then
EncodingSpecificOperations();
if read_spsr then
if CurrentModeIsUserOrSystem() then
UNPREDICTABLE;
else
R[d] = SPSR[];
else
// CPSR is read with execution state bits other than E masked out.
R[d] = CPSR AND ‘11111000 11111111 00000011 11011111’;
Exceptions
None.
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. B6-11