PSUBUSW         Subtract Unsigned with Saturation on Word

PSUBUSW destination, source                          CPU: MMX

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

    PSUBUSW subtracts the words of the source operand from the words of
    the destination operand and writes the results to the destination
    register.
    If the result element is less than zero (a negative value), it is
    saturated to 0000h.

    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 D9 /r    PSUBUSW mm, mm/m64