!
      module readmgcm
      integer,parameter :: nlon=72, nlat=36, nflds=4
      real,parameter :: glon1=-180., dlon=5., glat1=-87.5, dlat=5.
      real :: frd(nlon,nlat,nflds) ! global fields to be read (z,t,u,v)
      real :: xls,time
      real :: glat(nlat),glon(nlon)
      character(len=120) :: sourcefile
      contains
!-----------------------------------------------------------------------
      subroutine rdmgcm(filein,eof)
!
! Read a record from input file filein. Return eof==1 if EOF is encountered
! on this file. On first call, open the file. If eof encountered, close the file.
!
      implicit none
!
! Args:
      character(len=*),intent(in) :: filein
      integer,intent(out) :: eof
!
! Local:
      integer :: luread=20
      integer :: ier,ios,j,i
      integer :: nlonrd,nlatrd,nbinrd
      character(len=120) :: cmd
      logical :: exists,isopen
      real :: rdnlon,rdnlat,rdnbin
      integer,save :: ncalls=0,nrec=0
!
      ncalls = ncalls+1
      eof = 0
!
! Check for existence of input file:
      if (ncalls == 1) then
        write(6,"(/,'rdmgcm: Input Filename = ',a)") trim(filein)
        inquire(file=filein,exist=exists)
        if (exists) then
          write(6,"('File ',a,' exists.')") trim(filein)
        else
          write(6,"('>>> Cannot find file ',a)") trim(filein)
          stop 'mkcdf'
        endif
        sourcefile = filein
!
! Close luread if necessary:
        inquire(unit=luread,opened=isopen)
        if (isopen) then
          close(luread)
          write(6,"('Closed alread open unit ',i3)") luread
        endif
!
! Open for reading:
        open(unit=luread,file=trim(filein),status='OLD',
     |    form='UNFORMATTED',iostat=ios)
        if (ios /= 0) then
          write(6,"('>>> mkcdf: Error opening input file ',a,
     |      ' for reading: ios=',i4)") trim(filein),ios
          stop 'mkcdf'
        else
          write(6,"('Opened file ',a,' with luread=',i3)") 
     |      trim(filein),luread
        endif
!
! Define tgcm 5x5 degree grid:
        do j=1,nlat
          glat(j) = glat1+(j-1)*dlat
        enddo
        do i=1,nlon
          glon(i) = glon1+(i-1)*dlon
        enddo
      endif ! ncalls > 0
!
! 5/03 bf: Originally, these 4 floats were read from the 1st record, 
!          but no longer appears to be correct.
!
!     read(luread) rdnlon,rdnlat,rdnbin,xls
!     write(6,"('Read input file header: rdnlon=',f8.2,' rdnlat=',f8.2,
!    |  ' rdnbin=',f8.2,' xls=',f8.2)") rdnlon,rdnlat,rdnbin,xls
!     nlonrd = int(rdnlon)
!     nlatrd = int(rdnlat)
!     nbinrd= int(rdnbin)

      read(luread,end=900) frd,xls,time 
      nrec = nrec+1
!     write(6,"('nrec=',i4,' xls=',e12.4,' time=',e12.4)") 
!    |  nrec,xls,time
!     do j=1,nlat
!       write(6,"('f (z) at j=',i3,/,(6e12.4))") j,frd(:,j,1)
!     enddo
!     do j=1,nlat
!       write(6,"('f (t) at j=',i3,/,(6e12.4))") j,frd(:,j,2)
!     enddo
!     do j=1,nlat
!       write(6,"('f (u) at j=',i3,/,(6e12.4))") j,frd(:,j,3)
!     enddo
!     do j=1,nlat
!       write(6,"('f (v) at j=',i3,/,(6e12.4))") j,frd(:,j,4)
!     enddo
      return
 900  continue
      write(6,"('EOF encountered on input file ',a,' nrec=',i4)") 
     |  trim(filein),nrec
      eof = 1
      close(luread)
      end subroutine rdmgcm
      end module readmgcm