Command: XADD - Exchange and Add
Arguments: DEST: register or memory location, SRC: register
Usage: XADD DEST, SRC
Effects: XADD exchanges the values in its two operands, and then adds them together and writes the result into DEST.
Flags to be set: CF, PF, AF, SF, ZF, OF
Misc: This instruction can be used with a LOCK prefix for multi-processor synchronisation purposes.