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CPS

CPS (Change Processor State) changes one or more of the mode, A, I, and F bits in the CPSR, without changing the other CPSR bits.

CPS is only permitted in privileged software execution, and has no effect in User mode.

CPS cannot be conditional, and is not permitted in an IT block.

Syntax

CPSeffect iflags{, #mode}
CPS #mode

where:

effect

is one of:

IE

Interrupt or abort enable.

ID

Interrupt or abort disable.

iflags

is a sequence of one or more of:

a

Enables or disables imprecise aborts.

i

Enables or disables IRQ interrupts.

f

Enables or disables FIQ interrupts.

mode

specifies the number of the mode to change to.

Condition flags

This instruction does not change the condition flags.

16-bit instructions

The following forms of these instructions are available in Thumb code, and are 16-bit instructions:

  • CPSIE iflags

  • CPSID iflags

You cannot specify a mode change in a 16-bit Thumb instruction.

Architectures

This ARM instruction is available in ARMv6 and above.

This 32-bit Thumb instruction are available in ARMv6T2 and above.

This 16-bit Thumb instruction is available in T variants of ARMv6 and above.

Examples

    CPSIE if      ; enable interrupts and fast interrupts
    CPSID A       ; disable imprecise aborts
    CPSID ai, #17 ; disable imprecise aborts and interrupts, and enter FIQ mode
    CPS #16       ; enter User mode
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