The 8051 Instruction Set
Atmel 8051 Microcontrollers Hardware Manual 1-62
4316B–8051–02/04
1.14.51 XRL <dest-byte>,<src-byte>
Function: Logical Exclusive-OR for byte variables
Description: XRL performs the bitwise logical Exclusive-OR operation between the indicated variables, storing the results in
the destination. No flags are affected.
The two operands allow six addressing mode combinations. When the destination is the Accumulator, the source
can use register, direct, register-indirect, or immediate addressing; when the destination is a direct address, the
source can be the Accumulator or immediate data.
Note: When this instruction is used to modify an output port, the value used as the original port data is read from
the output data latch, not the input pins.
Example: If the Accumulator holds 0C3H (1100001lB) and register 0 holds 0AAH (10101010B) then the instruction,
XRL A,R0
leaves the Accumulator holding the value 69H (01101001B).
When the destination is a directly addressed byte, this instruction can complement combinations of bits in any
RAM location or hardware register. The pattern of bits to be complemented is then determined by a mask byte,
either a constant contained in the instruction or a variable computed in the Accumulator at run-time. The
following instruction,
XRL P1,#00110001B
complements bits 5, 4, and 0 of output Port 1.
XRL A,R
n
Bytes: 1
Cycles: 1
Encoding: 01101r r r
Operation: XRL
(A) ← (A) V
(R
n
)
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