ARM Cortex-M4 - Cps; Change Processor State

The Cortex-M4 Instruction Set
ARM DUI 0553A Copyright © 2010 ARM. All rights reserved. 3-159
ID121610 Non-Confidential
3.12.2 CPS
Change Processor State.
Syntax
CPSeffect iflags
where:
effect Is one of:
IE Clears the special purpose register.
ID Sets the special purpose register.
iflags Is a sequence of one or more flags:
i Set or clear PRIMASK.
f Set or clear FAULTMASK.
Operation
CPS changes the PRIMASK and FAULTMASK special register values. See Exception mask
registers on page 2-7 for more information about these registers.
Restrictions
The restrictions are:
•use
CPS only from privileged software, it has no effect if used in unprivileged software
•
CPS cannot be conditional and so must not be used inside an IT block.
Condition flags
This instruction does not change the condition flags.
Examples
CPSID i ; Disable interrupts and configurable fault handlers (set PRIMASK)
CPSID f ; Disable interrupts and all fault handlers (set FAULTMASK)
CPSIE i ; Enable interrupts and configurable fault handlers (clear PRIMASK)
CPSIE f ; Enable interrupts and fault handlers (clear FAULTMASK)