PSUBD           Subtraction with Wrap-around on Doubleword

PSUBD destination, source                            CPU: MMX

        Logic   mm(31..0)  <- mm(31..0)  - mm/m64(31..0)
                mm(63..32) <- mm(63..32) - mm/m64(63..32)

    PSUBD subtracts the doublewords of the source operand from the
    doublewords of the destination operand and returns the result to
    destination.
    When the result is too large or too small to be represented in a
    doubleword, the result wraps around and the lower 32 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 FA /r    PSUBD mm, mm/m64