Datasheet

185
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
Operation
The register access operation in MSR depends on the privilege level. Unprivileged software can only access the APSR.
See “Application Program Status Register” . 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
Rn is non-zero and less than the current BASEPRI value.
See “MRS” .
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
12.6.11.8 NOP
No Operation.
Syntax
NOP{cond}
where:
cond is an optional condition code, see “Conditional Execution” .
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