3.10.2. 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 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).
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