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XOR             XOR operation                        Flags: O D I T S Z A P C
                                                            0 - - - * * ? * 0
XOR destination,source

        Logic   destination . destination XOR source

    XOR performs a bit-by-bit "exclusive or" on its two operands, and
    returns the result in the destination operand. XOR sets each bit
    of the result to one if only one of the corresponding bits is set
    to one.

                          XOR truth table
                        a       b    a XOR b
                        0       0       0
                        0       1       1
                        1       0       1
                        1       1       0


        Example:        mov     al,110001b
                        xor     al,001101b
                        ;     al = 111100b

        Example:        xor     [mFlag],1       ; Flip 0->1, 1->0


    Opcode      Format
    30 /r       XOR  r/m8,r8
    31 /r       XOR  r/m16,r16
    31 /r       XOR  r/m32,r32
    32 /r       XOR  r8,r/m8
    33 /r       XOR  r16,r/m16
    33 /r       XOR  r32,r/m32
    34 ib       XOR  AL,imm8
    35 iw       XOR  AX,imm16
    35 id       XOR  EAX,imm32
    80 /6 ib    XOR  r/m8,imm8
    81 /6 iw    XOR  r/m16,imm16
    81 /6 id    XOR  r/m32,imm32
    83 /6 ib    XOR  r/m16,imm8
    83 /6 ib    XOR  r/m32,imm8


    Length and timing
    Operands    Bytes   8088    186     286     386     486     Pentium
    reg, reg     2       3       3       2       2       1       1   UV
    mem, reg  2+d(0,2)  24+EA   10       7       7       3       3   UV
    reg, mem  2+d(0,2)  13+EA   10       7       6       2       2   UV
    reg, imm  2+i(1,2)   4       4       3       2       1       1   UV
    mem, imm  2+d(0,2)  23+EA   16       7       7       3       3   UV*
               +i(1,2)
    acc, imm  1+i(1,2)   4       4       3       2       1       1   UV

        * = not pairable if there is a displacement and immediate