From 2f0b7f8df73536a8dd2e4678fee61a73b8a1506d Mon Sep 17 00:00:00 2001
From: Silvano Seva <silseva@fastwebnet.it>
Date: Thu, 21 Aug 2025 16:56:18 +0200
Subject: [PATCH] core: gps: added field for HDOP to GPS data

HDOP is expressed in cm, meaning that an HDOP of 1.37m is stored as 137 in
the GPS data structure.
---
 lib/minmea/include/minmea.h | 14 ++++++++++++++
 openrtx/include/core/gps.h  |  1 +
 openrtx/src/core/gps.c      |  2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/minmea/include/minmea.h b/lib/minmea/include/minmea.h
index da9aa54c..74f01b91 100644
--- a/lib/minmea/include/minmea.h
+++ b/lib/minmea/include/minmea.h
@@ -271,6 +271,20 @@ static inline int minmea_toint(struct minmea_float *f)
     return f->value / f->scale;
 }
 
+/**
+ * Convert a fixed-point value to an integer value, applying an additional
+ * scaling factor.
+ * Returns zero for "unknown" values.
+ */
+static inline int minmea_toscaledint(struct minmea_float *f, const int scale)
+{
+    if(f->scale == 0)
+        return 0;
+
+    int_least32_t tmp = f->value * scale;
+    return tmp / f->scale;
+}
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/openrtx/include/core/gps.h b/openrtx/include/core/gps.h
index dc9d2f98..af028ad1 100644
--- a/openrtx/include/core/gps.h
+++ b/openrtx/include/core/gps.h
@@ -54,6 +54,7 @@ typedef struct
     uint16_t   speed;                // Ground speed in km/h
     int16_t    tmg_mag;              // Course over ground, degrees, magnetic
     int16_t    tmg_true;             // Course over ground, degrees, true
+    uint16_t   hdop;                 // Horizontal dilution of precision, in cm
 }
 gps_t;
 
diff --git a/openrtx/src/core/gps.c b/openrtx/src/core/gps.c
index cd822045..8221049c 100644
--- a/openrtx/src/core/gps.c
+++ b/openrtx/src/core/gps.c
@@ -87,7 +87,6 @@ void gps_task(const struct gpsDevice *dev)
                 gps_data.timestamp.year = frame.date.year;
             }
 
-            gps_data.tmg_true = minmea_tofloat(&frame.course);
             gps_data.speed = KNOTS2KMH(minmea_toint(&frame.speed));
         }
         break;
@@ -110,6 +109,7 @@ void gps_task(const struct gpsDevice *dev)
             struct minmea_sentence_gsa frame;
             if (minmea_parse_gsa(&frame, sentence))
             {
+                gps_data.hdop = minmea_toscaledint(&frame.hdop, 100);
                 gps_data.fix_type = frame.fix_type;
                 for (int i = 0; i < 12; i++)
                 {