Fix G25 sequential shift direction

Per comments in #21, this fixes the Logitech G25 shifter's sequential shifting so that upshifting is towards the user and downshifting is away from the user, matching the markings on the shifter itself.

This changes the expected behavior of the up / down shift functions, but should maintain compatibility with existing user calibrations.

Author: dmadison

src/SimRacing.cpp

@@ -1421,7 +1421,7 @@ LogitechShifterG25::LogitechShifterG25(
 {
 	// using the calibration values from my own G25 shifter
 	this->setCalibration({ 508, 435 }, { 310, 843 }, { 303, 8 }, { 516, 827 }, { 540, 14 }, { 713, 846 }, { 704, 17 });
-	this->setCalibrationSequential(425, 619, 257);
+	this->setCalibrationSequential(425, 257, 619);
 }
 
 void LogitechShifterG25::begin() {
@@ -1463,17 +1463,17 @@ bool LogitechShifterG25::updateState(bool connected) {
 
 		// if we're neutral, check for up/down shift
 		if (this->sequentialState == 0) {
-			     if (y >= this->seqCalibration.upTrigger)   this->sequentialState =  1;
-			else if (y <= this->seqCalibration.downTrigger) this->sequentialState = -1;
+			     if (y <= this->seqCalibration.upTrigger)   this->sequentialState =  1;
+			else if (y >= this->seqCalibration.downTrigger) this->sequentialState = -1;
 		}
 
 		// if we're in up-shift mode, check for release
-		else if ((this->sequentialState == 1) && (y < this->seqCalibration.upRelease)) {
+		else if ((this->sequentialState == 1) && (y > this->seqCalibration.upRelease)) {
 			this->sequentialState = 0;
 		}
 
 		// if we're in down-shift mode, check for release
-		else if ((this->sequentialState == -1) && (y > this->seqCalibration.downRelease)) {
+		else if ((this->sequentialState == -1) && (y < this->seqCalibration.downRelease)) {
 			this->sequentialState = 0;
 		}
 
@@ -1526,16 +1526,35 @@ void LogitechShifterG25::setCalibrationSequential(int neutral, int up, int down,
 		releasePoint = engagePoint;
 	}
 
+	// if up/down calibration points are reversed, swap them
+	//
+	// in v2 of the library, pushing the shifter was 'shift up' and pulling the
+	// shifter was 'shift down'
+	//
+	// in v3 of the library this was fixed, so that pushing the shifter is
+	// 'shift down' and pulling the shifter is 'shift up', matching the
+	// markings on the shifter itself (or mine, at least). this also matches
+	// the behavior of a sequential shift lever in a real rally car
+	//
+	// by swapping the calibration points here, the function maintains
+	// compatibility with calibration lines written for both version of
+	// the library
+	if(up > down) {
+		int temp = up;
+		up = down;  // dogs and cats living together, mass hysteria
+		down = temp;
+	}
+
 	// calculate ranges
-	const int upRange   = up - neutral;
-	const int downRange = neutral - down;
+	const int upRange   = neutral - up;
+	const int downRange = down - neutral;
 
 	// calculate calibration points
-	this->seqCalibration.upTrigger   = neutral + (upRange * engagePoint);
-	this->seqCalibration.upRelease   = neutral + (upRange * releasePoint);
+	this->seqCalibration.upTrigger   = neutral - (upRange * engagePoint);
+	this->seqCalibration.upRelease   = neutral - (upRange * releasePoint);
 
-	this->seqCalibration.downTrigger = neutral - (downRange * engagePoint);
-	this->seqCalibration.downRelease = neutral - (downRange * releasePoint);
+	this->seqCalibration.downTrigger = neutral + (downRange * engagePoint);
+	this->seqCalibration.downRelease = neutral + (downRange * releasePoint);
 }
 
 void LogitechShifterG25::serialCalibrationSequential(Stream& iface) {
@@ -1582,14 +1601,14 @@ void LogitechShifterG25::serialCalibrationSequential(Stream& iface) {
 
 	const uint8_t NumPoints = 3;
 	const char* directions[2][2] = {
-		{ "away from you", "up" },
-		{ "towards you", "down" },
+		{ "towards you", "up" },
+		{ "away from you", "down" },
 	};
 	int data[NumPoints];
 
 	int& neutral = data[0];
-	int& yMax    = data[1];
-	int& yMin    = data[2];
+	int& yMin    = data[1];
+	int& yMax    = data[2];
 
 	for (uint8_t i = 0; i < NumPoints; ++i) {
 		if (i == 0) {
@@ -1635,7 +1654,7 @@ void LogitechShifterG25::serialCalibrationSequential(Stream& iface) {
 	flushClient(iface);
 
 	// apply and print
-	this->setCalibrationSequential(neutral, yMax, yMin, engagementPoint, releasePoint);
+	this->setCalibrationSequential(neutral, yMin, yMax, engagementPoint, releasePoint);
 
 	iface.println(F("Here is your calibration:"));
 	iface.println(separator);
@@ -1645,10 +1664,10 @@ void LogitechShifterG25::serialCalibrationSequential(Stream& iface) {
 
 	iface.print(neutral);
 	iface.print(", ");
-	iface.print(yMax);
-	iface.print(", ");
 	iface.print(yMin);
 	iface.print(", ");
+	iface.print(yMax);
+	iface.print(", ");
 
 	iface.print(engagementPoint);
 	iface.print(", ");