Adding some additional g2c interfaces (#584)

* add function g2c_get_pdt_len

* create g2c_get_gdt_len

* typo

* Update grib2.h.in

* Update tst_pdstemplates.c

* Update tst_get_grid_template.c

---------

Co-authored-by: Edward Hartnett <38856240+edwardhartnett@users.noreply.github.com>

Author: AlysonStahl-NOAA

src/grib2.h.in

@@ -331,7 +331,9 @@ int g2c_get_grid_template_extension(int grid_template_num, int *g2c_template,
                                     int *extlen, int *ext);
 int g2c_get_pds_template_extension(int pds_template_num, int *g2c_template,
                                    int *extlen, int *ext);
+int g2c_get_gdt_len(int grid_template_num, int *maplen);
 int g2c_get_pds_template(int pds_template_num, int *maplen, int *map, int *needext);
+int g2c_get_pdt_len(int pds_template_num, int *maplen);
 int g2c_get_drs_template(int drs_template_num, int *maplen, int *map, int *needext);
 
 /* Internal functions. */

src/gridtemplates.c

@@ -414,3 +414,39 @@ g2c_get_grid_template(int grid_template_num, int *maplen, int *map, int *needext
     /* If we didn't find a template, return an error. */
     return G2C_ENOTEMPLATE;
 }
+
+/**
+ * Get initial length (number of entries) in static part of 
+ * Grid Definition Template.
+ *
+ * @param grid_template_num The Grid template number.
+ * @param maplen Pointer that gets the length of the map. Ignored if
+ * NULL.
+ *
+ * @return
+ * - ::G2C_NOERROR No error.
+ * - ::G2C_ENOTEMPLATE Template not found.
+ *
+ * @author Alyson Stahl @date 01/21/25
+ */
+int
+g2c_get_gdt_len(int grid_template_num, int *maplen)
+{
+    int j;
+
+    /* Look through the array of templates to find a matching one. */
+    for (j = 0; j < G2C_MAX_GDS_TEMPLATE; j++)
+    {
+        if (grid_template_num == templatesgrid[j].template_num)
+        {
+            if (maplen)
+                *maplen = templatesgrid[j].mapgridlen;
+
+            /* Done. */
+            return G2C_NOERROR;
+        }
+    }
+
+    /* If we didn't find a template, return an error. */
+    return G2C_ENOTEMPLATE;
+}

src/pdstemplates.c

@@ -1829,3 +1829,38 @@ g2c_get_pds_template(int pds_template_num, int *maplen, int *map, int *needext)
     /* If we didn't find a template, return an error. */
     return G2C_ENOTEMPLATE;
 }
+
+/**
+ * Get initial length (number of entries) in static part of 
+ * PDS template.
+ *
+ * @param pds_template_num The PDS template number.
+ * @param maplen Pointer that gets the length of the map. Ignored if
+ * NULL.
+ *
+ * @return
+ * - ::G2C_NOERROR No error.
+ * - ::G2C_ENOTEMPLATE Template not found.
+ *
+ * @author Alyson Stahl @date 01/21/25
+ */
+int
+g2c_get_pdt_len(int pds_template_num, int *maplen)
+{
+    int j;
+
+    /* Look through the array of templates to find a matching one. */
+    for (j = 0; j < G2C_MAX_PDS_TEMPLATE; j++)
+    {
+        if (pds_template_num == templatespds[j].template_num)
+        {
+            if (maplen)
+                *maplen = templatespds[j].mappdslen;
+
+            return G2C_NOERROR;
+        }
+    }
+
+    /* If we didn't find a template, return an error. */
+    return G2C_ENOTEMPLATE;
+}

tests/tst_get_grid_template.c

@@ -141,6 +141,25 @@ main()
         }
     }
     printf("ok!\n");
+    printf("Testing g2c_get_gdt_len()\n");
+    {
+        int template_number[NUM_TESTS] = {
+            0, 1, 2, 3, 4, 5, 12, 101, 140, 10, 20, 30, 31, 40, 41, 42, 43, 50, 51, 52, 53, 90, 100, 110, 120,
+            204, 32768, 32769, 1000, 1100, 1200, 13, 23, 33, 61, 62, 63, 150};
+        int expected_maplen[NUM_TESTS] = {
+            19, 22, 22, 25, 13, 16, 22, 4, 17, 19, 18, 22, 22, 19, 22, 22, 25, 5, 8, 8, 11, 21, 11, 16, 7, 19,
+            19, 21, 20, 28, 16, 23, 22, 26, 23, 23, 26, 13};
+        int maplen, t, ret;
+
+        for (t = 0; t < NUM_TESTS; t++)
+        {
+            if ((ret = g2c_get_gdt_len(template_number[t], &maplen)))
+                return ret;
+            if (maplen != expected_maplen[t])
+                return G2C_ERROR;
+        }
+    }
+    printf("ok!\n");
     printf("SUCCESS!\n");
     return 0;
 }

tests/tst_pdstemplates.c

@@ -902,6 +902,16 @@ main()
                 free(tmpl);
             }
             printf("ok!\n");
+            printf("\tchecking g2c_get_pdt_len() with template %d...", number[t]);
+            {
+                int maplen, ret;
+
+                if ((ret = g2c_get_pdt_len(number[t], &maplen)))
+                    return ret;
+                if (maplen != expected_maplen[t])
+                    return G2C_ERROR;
+            }
+            printf("ok!\n");
             printf("\tchecking g2c_get_pds_template() with template %d...", number[t]);
             {
                 int maplen, needext;