adding open_index

src/g2c_interface.F90

@@ -15,11 +15,18 @@ function g2c_open(path, mode, g2idp) bind(c)
        integer(c_int) :: g2c_open
      end function g2c_open
 
+     function g2c_open_index(data_file, index_file, mode, g2cid) bind(c)
+       use iso_c_binding
+       character(kind=c_char), intent(in)  :: data_file(*), index_file(*)
+       integer(c_int), value :: mode
+       integer(c_int), intent(out) :: g2cid
+       integer(c_int) :: g2c_open_index
+     end function g2c_open_index
+
      function g2c_close(g2id) result(status)
        use iso_c_binding
        integer(c_int), intent(in) :: g2id
        integer(c_int) :: status
      end function g2c_close
-
   end interface
 end module g2c_interface

src/g2cf.F90

@@ -90,6 +90,48 @@ function g2cf_open(path, mode, g2id) result (status)
 
   end function g2cf_open
 
+  !> Open a GRIB2 file using an exsiting index file (generated by the
+  !> grb2index utility).
+  !>
+  !> @param data_file Path to data file.
+  !> @param index_file Path to index file.
+  !> @param mode Open mode, may be NC_CLOBBER (0) or NC_NOCLOBBER.
+  !> @param g2cid File ID.
+  !>
+  !> @return
+  !> - 0 No error
+  !>
+  !> @author Ed Hartnett @date 2022-11-21
+  function g2cf_open_index(data_file, index_file, mode, g2cid) result (status)
+    use iso_c_binding
+    implicit none
+
+    character(len=*), intent(in) :: data_file, index_file
+    integer, intent(in) :: mode
+    integer, intent(inout) :: g2cid
+    integer :: status
+
+    integer(c_int) :: cmode, cg2cid, cstatus
+    character(len = (len(data_file) + 1)) :: cdata_file
+    character(len = (len(index_file) + 1)) :: cindex_file
+    integer :: ie1, ie2
+
+    cmode = mode
+    cg2cid = 0
+
+    ! check for c null character on path and add one if not present.
+    cdata_file = addcnullchar(data_file, ie1)
+    cindex_file = addcnullchar(index_file, ie2)
+
+    ! call nc_create to create file
+    cstatus = g2c_open_index(cdata_file(1:ie1), cindex_file(1:ie2), cmode, cg2cid)
+
+    if (cstatus == 0) then
+       g2cid   = cg2cid
+    endif
+    status = cstatus
+  end function g2cf_open_index
+
   !> Close a GRIB2 file.
   !>
   !> @param g2id the ID of the open file