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C $Id: pltvwp.f,v 1.3 1993/07/19 17:06:45 gdsjaar Exp $
C $Log: pltvwp.f,v $
C Revision 1.3  1993/07/19 17:06:45  gdsjaar
C Changed hex constants back to preceding X, --needed on cray. Works
C either way on other systems.
C
c Revision 1.2  1993/07/16  17:33:23  gdsjaar
c Integer constant too big on sun, replaced it with hexadecimal notation
c
c Revision 1.1  1993/07/16  16:49:50  gdsjaar
c Changed plt to library rather than single source file.
c
C=======================================================================
      SUBROUTINE PLTVWP(PLL,PUR,N,MASK,PX,PY)
      REAL PLL(2),PUR(2)
      INTEGER MASK(*)
      REAL PX(*),PY(*)
      include 'izbit.inc'

      PUR1 = PUR(1) + .0001
      PUR2 = PUR(2) + .0001
      PLL1 = PLL(1) - .0001
      PLL2 = PLL(2) - .0001
      J = 0
      KM = 0
 2300 IF (.NOT. (J.LT.N)) GO TO 2310
      JN = MIN(N-J,32)
      J1 = J
      J = J + JN
      KM = KM + 1
      IF (MASK(KM).EQ.0) THEN
         GO TO 2300

      END IF

      DO 2320 K = 1,JN
         IF (IAND(MASK(KM),IZBIT(K)).EQ.0) THEN
            GO TO 2320

         END IF

         IF (PX(K+J1).LT.PLL1 .OR. PX(K+J1).GT.PUR1) THEN
            MASK(KM) = IAND(MASK(KM),NOT(IZBIT(K)))
            GO TO 2320

         END IF

         IF (PY(K+J1).LT.PLL2 .OR. PY(K+J1).GT.PUR2) THEN
            MASK(KM) = IAND(MASK(KM),NOT(IZBIT(K)))
            GO TO 2320

         END IF

 2320 CONTINUE
      GO TO 2300

 2310 CONTINUE
      RETURN

      END
