Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

192

Operation
The register access operation in MSR depends on the privilege level. Unprivileged software can only access the 

APSR. See 

. Privileged software can access all special registers.

In unprivileged software writes to unallocated or execution state bits in the PSR are ignored. 

Note:

When the user writes to BASEPRI_MAX, the instruction writes to BASEPRI only if either:
Rn

 is non-zero and the current BASEPRI value is 0

 is non-zero and less than the current BASEPRI value.

See 

Restrictions
Rn

 must not be SP and must not be PC.

Condition Flags
This instruction updates the flags explicitly based on the value in Rn.
Examples

MSR

CONTROL, R1 ; Read R1 value and write it to the CONTROL register 

No Operation.
Syntax

NOP{cond}

where:
condis an optional condition code, see 

.

Operation
NOP does nothing. NOP is not necessarily a time-consuming NOP. The processor might remove it from the 

pipeline before it reaches the execution stage.
Use NOP for padding, for example to place the following instruction on a 64-bit boundary.
Condition Flags
This instruction does not change the flags.
Examples

NOP

; No operation