jpcunpack.F90

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subroutine jpcunpack(cpack,len,idrstmpl,ndpts,fld)
  implicit none
  
  character(len=1),intent(in) :: cpack(len)
  integer,intent(in) :: ndpts,len
  integer,intent(in) :: idrstmpl(*)
  real,intent(out) :: fld(ndpts)
 
  integer :: ifld(ndpts)
  integer(4) :: ieee
  integer(8) :: len8
  real :: ref,bscale,dscale
  integer :: nbits, j, iret
 
  interface
     function dec_jpeg2000(cin, len, ifld) &
          bind(c, name="g2c_dec_jpeg2000")
       use iso_c_binding
       character(kind = c_char), intent(in) :: cin(*)
       integer(c_size_t), value, intent(in) :: len
       integer(c_int), intent(inout) :: ifld(*)
       integer(c_int) :: dec_jpeg2000
     end function dec_jpeg2000
  end interface
 
  ieee = idrstmpl(1)
  call rdieee(ieee,ref,1)
  bscale = 2.0**real(idrstmpl(2))
  dscale = 10.0**real(-idrstmpl(3))
  nbits = idrstmpl(4)
 
  !  if nbits equals 0, we have a constant field where the reference value
  !  is the data value at each gridpoint
  if (nbits.ne.0) then
     !         call g2_gbytesc(cpack,ifld,0,nbits,0,ndpts)
     len8 = len
     iret=dec_jpeg2000(cpack,len8,ifld)
     do j=1,ndpts
        fld(j)=((real(ifld(j))*bscale)+ref)*dscale
     enddo
  else
     do j=1,ndpts
        fld(j)=ref
     enddo
  endif
 
end subroutine jpcunpack