From c7e8a258f39389fca45803dca2107b0be614b4cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niccol=C3=B2=20Izzo?= <izzo.niccolo@gmail.com>
Date: Sat, 13 Feb 2021 11:20:06 +0100
Subject: [PATCH] Add active satellite field in GPS data

Now for each satellite in view we are keeping track if it's part of a
fix or not. This information is represented by a yellow color in the bar
graph screen.
---
 openrtx/include/state.h |  1 +
 openrtx/src/gps.c       | 31 +++++++++++++++++++++++++++----
 openrtx/src/graphics.c  |  7 ++++---
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/openrtx/include/state.h b/openrtx/include/state.h
index a570a856..806afb49 100644
--- a/openrtx/include/state.h
+++ b/openrtx/include/state.h
@@ -35,6 +35,7 @@ typedef struct
     uint8_t elevation;    // Elevation in degrees
     uint16_t azimuth;     // Azimuth in degrees
     uint8_t snr;          // Quality of the signal in range 0-99
+    bool active;          // True if this satellite is part of the fix
 }
 sat_t;
 
diff --git a/openrtx/src/gps.c b/openrtx/src/gps.c
index bfd3e8e2..654de64e 100644
--- a/openrtx/src/gps.c
+++ b/openrtx/src/gps.c
@@ -48,7 +48,8 @@ void gps_taskFunc(char *line, int len, gps_t *state)
         case MINMEA_SENTENCE_GGA:
         {
             struct minmea_sentence_gga frame;
-            if (minmea_parse_gga(&frame, line)) {
+            if (minmea_parse_gga(&frame, line))
+            {
                 state->fix_quality = frame.fix_quality;
                 state->satellites_tracked = frame.satellites_tracked;
                 state->altitude = minmea_tofloat(&frame.altitude);
@@ -58,23 +59,45 @@ void gps_taskFunc(char *line, int len, gps_t *state)
         case MINMEA_SENTENCE_GSA:
         {
             struct minmea_sentence_gsa frame;
-            if (minmea_parse_gsa(&frame, line)) {
+            if (minmea_parse_gsa(&frame, line))
+            {
                 state->fix_type = frame.fix_type;
+                for (int i = 0; i < 12; i++)
+                {
+                    if (frame.sats[i] != 0)
+                    {
+                        for (int j = 0; j < 12; j++)
+                        {
+                            if (state->satellites[j].id == frame.sats[i])
+                            {
+                                state->satellites[j].active = true;
+                                break;
+                            }
+                        }
+                    }
+                }
             }
         } break;
 
         case MINMEA_SENTENCE_GSV:
         {
             struct minmea_sentence_gsv frame;
-            if (minmea_parse_gsv(&frame, line)) {
+            if (minmea_parse_gsv(&frame, line))
+            {
                 state->satellites_in_view = frame.total_sats; 
-                for (int i = 0; i < 4; i++) {
+                for (int i = 0; i < 4; i++)
+                {
                     int index = 4 * (frame.msg_nr - 1) + i;
                     state->satellites[index].id = frame.sats[i].nr;
                     state->satellites[index].elevation = frame.sats[i].elevation;
                     state->satellites[index].azimuth = frame.sats[i].azimuth;
                     state->satellites[index].snr = frame.sats[i].snr;
+                    state->satellites[index].active = false;
                 }
+                // Zero out unused satellite slots
+                if (frame.msg_nr == frame.total_msgs && frame.total_msgs < 3)
+                    bzero(&state->satellites[4 * frame.msg_nr],
+                          sizeof(sat_t) * 12 - frame.total_msgs * 4);
             }
         } break;
 
diff --git a/openrtx/src/graphics.c b/openrtx/src/graphics.c
index e1a6e9cc..807682ca 100644
--- a/openrtx/src/graphics.c
+++ b/openrtx/src/graphics.c
@@ -555,10 +555,11 @@ void gfx_drawGPSgraph(point_t start,
         bar_height = (height - 8) * sats[i].snr / 100 + 1;
         point_t bar_pos = {start.x + 2 + i * (bar_width + 2),
                            start.y + (height - 8) - bar_height};
-        gfx_drawRect(bar_pos, bar_width, bar_height, white, true);
+        color_t bar_color = (sats[i].active) ? yellow : white;
+        gfx_drawRect(bar_pos, bar_width, bar_height, bar_color, true);
         snprintf(id_buf, 5, "%2d ", sats[i].id);
-        point_t id_start = {bar_pos.x, start.y + height};
-        gfx_print(id_start, id_buf, FONT_SIZE_5PT, TEXT_ALIGN_LEFT, white);
+        point_t id_pos = {bar_pos.x, start.y + height};
+        gfx_print(id_pos, id_buf, FONT_SIZE_5PT, TEXT_ALIGN_LEFT, white);
     }
     uint8_t bars_width = 9 + 11 * (bar_width + 2);
     point_t left_line_end = {start.x, start.y + height - 9};