PSUBSW          Subtract Signed with Saturation on Word

PSUBSW destination, source                           CPU: MMX

        Logic
        mm(15..0)  <- SaturateToSignedWord (mm(15..0)  - mm/m64(15..0) )
        mm(31..16) <- SaturateToSignedWord (mm(31..16) - mm/m64(31..16))
        mm(47..32) <- SaturateToSignedWord (mm(47..32) - mm/m64(47..32))
        mm(63..48) <- SaturateToSignedWord (mm(63..48) - mm/m64(63..48))

    PSUBSW subtracts the signed words of the source operand from the
    signed words of the destination operand, and writes the results to
    the destination register.
    If the result is larger or smaller than the range of a signed word,
    the value is saturated; in the case of an overflow - to 7FFFh, and
    in the case of an underflow - to 8000h.

    The destination operand is an MMX register. The source operand can
    either be an MMX register or a 64-bit memory operand. 


    Opcode      Format
    0F E9 /r    PSUBSW mm, mm/m64