Datasheet

115
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
12.6.5.5 CMP and CMN
Compare and Compare Negative.
Syntax
CMP{cond} Rn, Operand2
CMN{cond} Rn, Operand2
where:
cond is an optional condition code, see “Conditional Execution” .
Rn is the register holding the first operand.
Operand2 is a flexible second operand. See “Flexible Second Operand” for details of the
options
Operation
These instructions compare the value in a register with Operand2. They update the condition flags on the result,
but do not write the result to a register.
The CMP instruction subtracts the value of Operand2 from the value in Rn. This is the same as a SUBS
instruction, except that the result is discarded.
The CMN instruction adds the value of Operand2 to the value in Rn. This is the same as an ADDS instruction,
except that the result is discarded.
Restrictions
In these instructions:
 Do not use PC
 Operand2 must not be SP.
Condition Flags
These instructions update the N, Z, C and V flags according to the result.
Examples
CMP R2, R9
CMN R0, #6400
CMPGT SP, R7, LSL #2