NAME
        SetSR -- get and/or set processor status register

   SYNOPSIS
        oldSR = SetSR(newSR, mask)
        D0            D0     D1

        ULONG SetSR(ULONG, ULONG);

   FUNCTION
        This function provides a means of modifying the CPU status register
        in a "safe" way (well, how safe can a function like this be
        anyway?).  This function will only affect the status register bits
        specified in the mask parameter.  The prior content of the entire
        status register is returned.

   INPUTS
        newSR - new values for bits specified in the mask.
            All other bits are not effected.
        mask - bits to be changed

   RESULTS
        oldSR - the entire status register before new bits

   EXAMPLES
        To get the current SR:
            currentSR = SetSR(0,0);
        To change the processor interrupt level to 3:
            oldSR = SetSR($0300,$0700);
        Set processor interrupts back to prior level:
            SetSR(oldSR,$0700);