PSUBW           Subtraction with Wrap-around on Word

PSUBW destination, source                            CPU: MMX

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

    PSUBW subtracts the words of the source operand from the words of
    the destination operand and returns the result to destination.
    When the result is too large or too small to be represented in a
    word, the result wraps around and the lower 16 bits are written to
    the destination register.

    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 F9 /r    PSUBW mm, mm/m64