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CMP             Compare                              Flags: O D I T S Z A P C
                                                            * - - - * * * * *
CMP destination,source

        Logic   Flags set according to result of
                (destination - source)

    CMP compares two numbers by subtracting the source from the
    destination and updates the flags. None of the operands are
    changed by CMP.


    Opcode      Format
    38 /r       CMP  r/m8,r8
    39 /r       CMP  r/m16,r16
    39 /r       CMP  r/m32,r32
    3A /r       CMP  r8,r/m8
    3B /r       CMP  r16,r/m16
    3B /r       CMP  r32,r/m32
    3C ib       CMP  AL,imm8
    3D iw       CMP  AX,imm16
    3D id       CMP  EAX,imm32
    80 /7 ib    CMP  r/m8,imm8
    81 /7 iw    CMP  r/m16,imm16
    81 /7 id    CMP  r/m32,imm32
    83 /7 ib    CMP  r/m16,imm8
    83 /7 ib    CMP  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)  13+EA   10       7       5       2       2   UV
    reg, mem  2+d(0,2)  13+EA   10       6       6       2       2   UV
    reg, imm  2+i(1,2)   4       4       3       2       1       1   UV
    mem, imm  2+d(0,2)  14+EA   10       6       5       2       2   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