PADDSB          Add Signed with Saturation on Byte

PADDSB destination, source                           CPU: MMX

        Logic   
        mm(7..0)   <- SaturateToSignedByte( mm(7..0)   + mm/m64 (7..0)  )
        mm(15..8)  <- SaturateToSignedByte( mm(15..8)  + mm/m64(15..8)  )
        mm(23..16) <- SaturateToSignedByte( mm(23..16) + mm/m64(23..16) )
        mm(31..24) <- SaturateToSignedByte( mm(31..24) + mm/m64(31..24) )
        mm(39..32) <- SaturateToSignedByte( mm(39..32) + mm/m64(39..32) )
        mm(47..40) <- SaturateToSignedByte( mm(47..40) + mm/m64(47..40) )
        mm(55..48) <- SaturateToSignedByte( mm(55..48) + mm/m64(55..48) )
        mm(63..56) <- SaturateToSignedByte( mm(63..56) + mm/m64(63..56) )

    PADDSB adds the signed bytes of the source operand to the signed
    bytes of the destination operand and writes the results to the
    destination MMX register.

    If the result is larger or smaller than the range of a signed byte,
    the value is saturated (in the case of an overflow to 7Fh, and in
    the case of an underflow to 80h.

    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 EC /r    PADDSB mm/m64