From 552d6eaacad432a9422759705d93451e1a4561f5 Mon Sep 17 00:00:00 2001
From: robertl <robertl@f51c46e8-681c-474f-0cfe-069cfd0219fb>
Date: Thu, 15 Sep 2005 01:53:04 +0000
Subject: [PATCH] Allow Natl Topo to allow override of datums for benefit of
 users in HI.

---
 gpsbabel/README          |  6 ++++++
 gpsbabel/jeeps/gpsmath.c | 13 +++++++++++++
 gpsbabel/jeeps/gpsmath.h |  2 ++
 gpsbabel/tpg.c           | 25 ++++++++++++++++++++++---
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/gpsbabel/README b/gpsbabel/README
index c6031e741..cba352a24 100644
--- a/gpsbabel/README
+++ b/gpsbabel/README
@@ -470,6 +470,12 @@ THE FORMATS
 	National Geographic Topo! Waypoint Format.  This filter 
 	reads and writes .TPG files created by various editions of NG Topo! 
 	This filter will *not* work with the newer combined .TPO files.  
+
+        The option 'datum="datum name"' can be used to override the
+        default of NAD27 ("N. America 1927 mean") which is correct
+        for the continental U.S. Points in Hawaii should use "Old
+        Hawaiian_mean"
+
 	Contributed by Alex Mottram.
 
     HOLUX
diff --git a/gpsbabel/jeeps/gpsmath.c b/gpsbabel/jeeps/gpsmath.c
index e3a9284a7..ac412f196 100644
--- a/gpsbabel/jeeps/gpsmath.c
+++ b/gpsbabel/jeeps/gpsmath.c
@@ -1797,3 +1797,16 @@ int32 GPS_Math_UTM_EN_To_WGS84(double *lat, double *lon, double E,
 
     return 1;
 }
+
+int32 GPS_Lookup_Datum_Index(const char *n)
+{
+	GPS_PDatum dp;
+
+	for (dp = GPS_Datum; dp->name; dp++) {
+		if (0 == case_ignore_strcmp(dp->name, n)) {
+			return dp - GPS_Datum;
+		}
+	}
+
+	return -1;
+}
diff --git a/gpsbabel/jeeps/gpsmath.h b/gpsbabel/jeeps/gpsmath.h
index 4e2249f08..e308b8514 100644
--- a/gpsbabel/jeeps/gpsmath.h
+++ b/gpsbabel/jeeps/gpsmath.h
@@ -116,6 +116,8 @@ int32 GPS_Math_UTM_EN_To_WGS84(double *lat, double *lon, double E,
 int32 GPS_Math_UTM_EN_To_NAD83(double *lat, double *lon, double E,
 			       double N, int32 zone, char zc);
 
+int32 GPS_Lookup_Datum_Index(const char *n);
+
 #endif
 
 #ifdef __cplusplus
diff --git a/gpsbabel/tpg.c b/gpsbabel/tpg.c
index 81b80daf0..1c2022d42 100644
--- a/gpsbabel/tpg.c
+++ b/gpsbabel/tpg.c
@@ -33,9 +33,17 @@
 static FILE *tpg_file_in;
 static FILE *tpg_file_out;
 static void *mkshort_handle;
+static char *tpg_datum_opt;
+static int tpg_datum_idx;
 
 static unsigned int waypt_out_count;
 
+static
+arglist_t tpg_args[] = {
+	{"datum", &tpg_datum_opt, "Datum (default=NAD27)", "N. America 1927 mean", ARGTYPE_STRING },
+	{0, 0, 0, 0, 0}
+};
+
 static int
 tpg_fread(void *buff, size_t size, size_t members, FILE * fp) 
 {
@@ -85,9 +93,19 @@ valid_tpg_header(char * header, int len)
     return memcmp(header_bytes, header, len);
 }
 
+static void
+tpg_common_init(void)
+{
+	tpg_datum_idx = GPS_Lookup_Datum_Index(tpg_datum_opt);
+	if (tpg_datum_idx < 0) {
+		fatal(MYNAME ": Datum '%s' is not recognized.\n", tpg_datum_opt);
+	}
+}
+
 static void
 tpg_rd_init(const char *fname)
 {
+	tpg_common_init();
 	tpg_file_in = xfopen(fname, "rb", MYNAME);
 }
 
@@ -100,6 +118,7 @@ tpg_rd_deinit(void)
 static void
 tpg_wr_init(const char *fname)
 {
+	tpg_common_init();
 	tpg_file_out = xfopen(fname, "wb", MYNAME);
 	mkshort_handle = mkshort_new_handle();
 	waypt_out_count = 0;
@@ -172,7 +191,7 @@ tpg_read(void)
                 &wpt_tmp->latitude,
                 &wpt_tmp->longitude,
                 &amt,
-                78);
+                tpg_datum_idx);
 
             wpt_tmp->altitude = elev;
             
@@ -255,7 +274,7 @@ tpg_waypt_pr(const waypoint *wpt)
                 &lat,
                 &lon,
                 &amt,
-                78);
+                tpg_datum_idx);
         
 
         /* swap the sign back *after* the datum conversion */
@@ -365,6 +384,6 @@ ff_vecs_t tpg_vecs = {
 	tpg_read,
 	tpg_write,
 	NULL,
-	NULL,
+	tpg_args,
 	CET_CHARSET_ASCII, 0	/* CET-REVIEW */
 };
-- 
2.30.2