CDECK  ID>, HWSGEN.

*CMZ :-        -26/04/91  14.55.45  by  Federico Carminati

*-- Author :    Bryan Webber

C-----------------------------------------------------------------------

      SUBROUTINE HWSGEN(GENEX)

C-----------------------------------------------------------------------

C     GENERATES X VALUES (IF GENEX)

C     EVALUATES STRUCTURE FUNCTIONS AND ENFORCES CUTOFFS ON X

C-----------------------------------------------------------------------

      INCLUDE 'HERWIG61.INC'

      DOUBLE PRECISION HWBVMC,HWRUNI,X,QL

      INTEGER I,J

      LOGICAL GENEX

      EXTERNAL HWBVMC,HWRUNI

      IF (GENEX) THEN

        XX(1)=EXP(HWRUNI(0,ZERO,XLMIN))

        XX(2)=XXMIN/XX(1)

      ENDIF

      DO 10 I=1,2

        J=I

        IF (JDAHEP(1,I).NE.0) J=JDAHEP(1,I)

        X=XX(I)

        QL=(1.-X)*EMSCA

        CALL HWSFUN(X,EMSCA,IDHW(J),NSTRU,DISF(1,I),I)

      DO 10 J=1,13

        IF (QL.LT.HWBVMC(J)) DISF(J,I)=0.

   10 CONTINUE

      END