From 93635f62aac42d6c816d89def7532bac7c6db069 Mon Sep 17 00:00:00 2001
From: David Boone <dave@MacBook>
Date: Tue, 10 Sep 2019 10:54:07 -0700
Subject: [PATCH] Efficiency OSD element in mAh/km or mAh/mi

---
 src/main/cli/settings.c     |  1 +
 src/main/osd/osd.h          |  1 +
 src/main/osd/osd_elements.c | 25 +++++++++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/src/main/cli/settings.c b/src/main/cli/settings.c
index 73ae91573d..a688d4e8a8 100644
--- a/src/main/cli/settings.c
+++ b/src/main/cli/settings.c
@@ -1342,6 +1342,7 @@ const clivalue_t valueTable[] = {
 
     { "osd_rcchannels_pos",     VAR_UINT16  | MASTER_VALUE, .config.minmaxUnsigned = { 0, OSD_POSCFG_MAX }, PG_OSD_ELEMENT_CONFIG, offsetof(osdElementConfig_t, item_pos[OSD_RC_CHANNELS]) },
     { "osd_camera_frame_pos",   VAR_UINT16  | MASTER_VALUE, .config.minmaxUnsigned = { 0, OSD_POSCFG_MAX }, PG_OSD_ELEMENT_CONFIG, offsetof(osdElementConfig_t, item_pos[OSD_CAMERA_FRAME]) },
+    { "osd_efficiency_pos",     VAR_UINT16  | MASTER_VALUE, .config.minmaxUnsigned = { 0, OSD_POSCFG_MAX }, PG_OSD_ELEMENT_CONFIG, offsetof(osdElementConfig_t, item_pos[OSD_EFFICIENCY]) },
 
     // OSD stats enabled flags are stored as bitmapped values inside a 32bit parameter
     // It is recommended to keep the settings order the same as the enumeration. This way the settings are displayed in the cli in the same order making it easier on the users
diff --git a/src/main/osd/osd.h b/src/main/osd/osd.h
index fd3b197fc9..128228f228 100644
--- a/src/main/osd/osd.h
+++ b/src/main/osd/osd.h
@@ -143,6 +143,7 @@ typedef enum {
     OSD_RSSI_DBM_VALUE,
     OSD_RC_CHANNELS,
     OSD_CAMERA_FRAME,
+    OSD_EFFICIENCY,
     OSD_ITEM_COUNT // MUST BE LAST
 } osd_items_e;
 
diff --git a/src/main/osd/osd_elements.c b/src/main/osd/osd_elements.c
index 9223fb0bfd..73ded33bcf 100644
--- a/src/main/osd/osd_elements.c
+++ b/src/main/osd/osd_elements.c
@@ -136,6 +136,7 @@
 #define OSD_STICK_OVERLAY_VERTICAL_POSITIONS (OSD_STICK_OVERLAY_HEIGHT * OSD_STICK_OVERLAY_SPRITE_HEIGHT)
 
 #define FULL_CIRCLE 360
+#define EFFICIENCY_MINIMUM_SPEED_CM_S 100
 
 #ifdef USE_OSD_STICK_OVERLAY
 typedef struct radioControls_s {
@@ -922,6 +923,26 @@ static void osdElementGpsSpeed(osdElementParms_t *element)
 {
     tfp_sprintf(element->buff, "%c%3d%c", SYM_SPEED, osdGetSpeedToSelectedUnit(gpsConfig()->gps_use_3d_speed ? gpsSol.speed3d : gpsSol.groundSpeed), osdGetSpeedToSelectedUnitSymbol());
 }
+
+static void osdElementEfficiency(osdElementParms_t *element)
+{
+    int efficiency = 0;
+    if (sensors(SENSOR_GPS) && ARMING_FLAG(ARMED) && STATE(GPS_FIX) && gpsSol.groundSpeed >= EFFICIENCY_MINIMUM_SPEED_CM_S) {
+        const int speedX100 = osdGetSpeedToSelectedUnit(gpsSol.groundSpeed * 100); // speed * 100 for improved resolution at slow speeds
+        
+        if (speedX100 > 0) {
+            const int mAmperage = getAmperage() * 10; // Current in mA
+            efficiency = mAmperage * 100 / speedX100; // mAmperage * 100 to cancel out speed * 100 from above
+        }
+    }
+
+    const char unitSymbol = osdConfig()->units == OSD_UNIT_IMPERIAL ? SYM_MILES : SYM_KM;
+    if (efficiency > 0 && efficiency <= 9999) {
+        tfp_sprintf(element->buff, "%4d%c/%c", efficiency, SYM_MAH, unitSymbol);
+    } else {
+        tfp_sprintf(element->buff, "----%c/%c", SYM_MAH, unitSymbol);
+    }
+}
 #endif // USE_GPS
 
 static void osdBackgroundHorizonSidebars(osdElementParms_t *element)
@@ -1697,6 +1718,9 @@ const osdElementDrawFn osdElementDrawFunction[OSD_ITEM_COUNT] = {
     [OSD_RSSI_DBM_VALUE]          = osdElementRssiDbm,
 #endif
     [OSD_RC_CHANNELS]             = osdElementRcChannels,
+#ifdef USE_GPS
+    [OSD_EFFICIENCY]              = osdElementEfficiency,
+#endif
 };
 
 // Define the mapping between the OSD element id and the function to draw its background (static part)
@@ -1748,6 +1772,7 @@ void osdAddActiveElements(void)
         osdAddActiveElement(OSD_HOME_DIST);
         osdAddActiveElement(OSD_HOME_DIR);
         osdAddActiveElement(OSD_FLIGHT_DIST);
+        osdAddActiveElement(OSD_EFFICIENCY);
     }
 #endif // GPS
 #ifdef USE_ESC_SENSOR