Off-line initialization of a processor

In case the initialization part of a processor is bulky it may be convenient to split it off from the processor proper into a separate subroutine to be called just once from the root, so as to have it executed and then out of the way. Suppose we have the processor BB, and we split the initialization off into subroutine BBIN. This might then look as follows:

      SUBROUTINE BBIN

+CDE, Q.

      CALL JZIN ('BB  ',0,36,0)
      IF (IQUEST(1))         11, 17, 99

C--       Initialize constants if and only if not set from title
   11 Q(LQAN+1) = .0025
      Q(LQAN+2) = .3

C--       Complete initialization calculating derived constants
   17 Q(LQAN+3) = .5 * SIN (Q(LQAN+2))

      IQ(LQSV+2) = 0       to reset the entry count from 1 to zero
   99 CALL JZOUT ('BB  ')
      RETURN
      END
C=====================================================

      SUBROUTINE BB

+CDE, Q.

      CALL JZIN ('BB  ',0,0,0)
      IF (IQUEST(1).LE.0)  CALL ZFATAM ('BB, NOT INITIALIZED.')
      CALL MZWORK (...)

         processor body

      CALL JZOUT ('BB  ')
      RETURN
      END
C=====================================================

Note that in subroutine BB it is still wise to check on IQUEST(1) in case the explicit CALL BBIN from the main program has been lost.