From cd05c3da86c053c2848d8ddc8138286a2e84e83e Mon Sep 17 00:00:00 2001
From: Edward Hartnett <edward.hartnett@noaa.gov>
Date: Sat, 21 Dec 2024 08:40:56 -0700
Subject: [PATCH] more progress

---
 src/g2c_interface.F90 | 13 ++++++++++++-
 src/g2cf.F90          | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/g2c_interface.F90 b/src/g2c_interface.F90
index 8418a99f..05c145ca 100644
--- a/src/g2c_interface.F90
+++ b/src/g2c_interface.F90
@@ -30,7 +30,18 @@ function g2c_inq(g2id, num_msg) bind(c)
        integer(c_int) :: g2c_inq
      end function g2c_inq
 
-     ! int g2c_inq(int g2cid, int *num_msg);
+     function g2c_inq_msg(g2id, msg_num, discipline, num_fields, &
+          num_local, center, subcenter, master_version, local_version) bind(c)
+       use iso_c_binding
+       integer(c_int), value :: g2id
+       integer(c_int), intent(in) :: msg_num
+       integer(c_signed_char), intent(out) :: discipline
+       integer(c_int), intent(out) :: num_fields, num_local
+       integer(c_short), intent(out) :: center, subcenter
+       integer(c_signed_char), intent(out) :: master_version, local_version
+       integer(c_int) :: g2c_inq_msg
+     end function g2c_inq_msg
+
      ! int g2c_inq_msg(int g2cid, int msg_num, unsigned char *discipline, int *num_fields,
      !    int *num_local, short *center, short *subcenter, unsigned char *master_version,
      !    unsigned char *local_version);
diff --git a/src/g2cf.F90 b/src/g2cf.F90
index a46d3add..816e20bf 100644
--- a/src/g2cf.F90
+++ b/src/g2cf.F90
@@ -157,6 +157,43 @@ function g2cf_inq(g2id, num_msg) result(status)
     status = cstatus
   end function g2cf_inq
 
+  !> Learn about a message are in a GRIB2 file.
+  !>
+  !> @param[in] g2id The ID of the open file
+  !> @param[in] msg_num The number of message to learn about.
+  !> @param[out] discipline The discipline of the message.
+  !> @param[out] num_fields Number of fields in the message.
+  !> @param[out] num_local Number of local sections in the message.
+  !> @param[out] center Originating center.
+  !> @param[out] subcenter Originating sub-center.
+  !> @param[out] master_version Master version.
+  !> @param[out] local_version Local version.
+  !>
+  !> @return 0 for success, error code otherwise.
+  !>
+  !> @author Edward Hartnett @date 2024-12-21
+  function g2cf_inq_msg(g2id, msg_num, discipline, num_fields, &
+          num_local, center, subcenter, master_version, local_version) result(status)
+    use iso_c_binding    
+    use g2c_interface
+    implicit none
+    
+    integer, intent(in) :: g2id
+    integer(c_int), intent(in) :: msg_num
+    integer(c_signed_char), intent(out) :: discipline
+    integer(c_int), intent(out) :: num_fields, num_local
+    integer(c_short), intent(out) :: center, subcenter
+    integer(c_signed_char), intent(out) :: master_version, local_version
+    integer :: status
+    
+    integer(c_int) :: cg2id, cnum_msg, cstatus
+
+    cg2id = g2id
+    cstatus = g2c_inq(cg2id, cnum_msg)
+    !num_msg = cnum_msg
+    status = cstatus
+  end function g2cf_inq_msg
+
   !> Close a GRIB2 file.
   !>
   !> @param g2id The ID of the open file