@instruction<EOL><INDENT>def PXOR(cpu, dest, src):<DEDENT>
res = dest.write(dest.read() ^ src.read())<EOL>
Logical exclusive OR.

Performs a bitwise logical exclusive-OR (XOR) operation on the quadword
source (second) and destination (first) operands and stores the result
in the destination operand location. The source operand can be an MMX(TM)
technology register or a quadword memory location; the destination operand
must be an MMX register. Each bit of the result is 1 if the corresponding
bits of the two operands are different; each bit is 0 if the corresponding
bits of the operands are the same::

    DEST  =  DEST XOR SRC;

:param cpu: current CPU.
:param dest: destination operand.
:param src: quadword source operand.