subroutine bitmsk (iw7, imask, nbsht, ians)
c
c-----------------------------------------------------------------------
c     This routine determines instrument flags from word 7's
c
c     Do not change these integer*2s to integer*4s
c-----------------------------------------------------------------------
c
      logical*1 ibyte(2),iw7
c
      integer*2 bytand, byte2, ians, imask, iw7b2, nbsht
c
      equivalence (byte2,ibyte(1))
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      iw7b2 = iw7
c
c-----------------------------------------------------------------------
c     *** both iand and ishft must have two integer*2 arguments ***
c-----------------------------------------------------------------------
c
      bytand = iand(iw7b2, imask)
      byte2 = ishft(bytand, nbsht)
c
c-----------------------------------------------------------------------
c     *** ians = ibyte(2),ibyte(1) in this order ***
c-----------------------------------------------------------------------
c
      ians = ibyte(1)
c
c-----------------------------------------------------------------------
c-----------------------------------------------------------------------
c
      return
      end