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  • The xor instruction performs a logical XOR (exclusive OR) operation.
  • This is the equivalent to the "^" operator in python:
>>> hex(0x18 ^ 0x7575)


xor destination, value

Affected flags

  • The OF and CF flags are cleared
  • The SF, ZF, and PF flags are set according to the result
  • The state of the AF flag is undefined.


mov eax, 0x18   ;11000 in binary
xor eax, 0x7575  ;111010101110101 in  binary

The above example will store 0x756D (111010101101101 in binary) into EAX.

00000000 00011000
01110101 01110101
01110101 01101101

For optimization purposes (it only requires 2 bytes), the xor instruction is often used that way to clear the value of a register:

xor eax, eax  ; clears the EAX register