Float and better 3rd party library compatibility (#2534)

* define as float (not double)

* Avoid #define of 1 or 2 char symbols

Having this file define 'A' and 'C' pollutes
the global namespace, and causes conflicts
with other libraries that also pollute the
global namespace with short #defines.
It's easier to fix this header.

* unused variable warning

usermods/SN_Photoresistor/usermod_sn_photoresistor.h

@@ -22,12 +22,12 @@
 
 // 10 bits
 #ifndef USERMOD_SN_PHOTORESISTOR_ADC_PRECISION
-#define USERMOD_SN_PHOTORESISTOR_ADC_PRECISION 1024.0
+#define USERMOD_SN_PHOTORESISTOR_ADC_PRECISION 1024.0f
 #endif
 
 // resistor size 10K hms
 #ifndef USERMOD_SN_PHOTORESISTOR_RESISTOR_VALUE
-#define USERMOD_SN_PHOTORESISTOR_RESISTOR_VALUE 10000.0
+#define USERMOD_SN_PHOTORESISTOR_RESISTOR_VALUE 10000.0f
 #endif
 
 // only report if differance grater than offset value

usermods/battery_status_basic/usermod_v2_battery_status_basic.h

@@ -21,10 +21,10 @@
 #ifndef USERMOD_BATTERY_ADC_PRECISION
   #ifdef ARDUINO_ARCH_ESP32
     // 12 bits
-    #define USERMOD_BATTERY_ADC_PRECISION 4095.0
+    #define USERMOD_BATTERY_ADC_PRECISION 4095.0f
   #else
     // 10 bits
-    #define USERMOD_BATTERY_ADC_PRECISION 1024.0
+    #define USERMOD_BATTERY_ADC_PRECISION 1024.0f
   #endif
 #endif
 
@@ -39,11 +39,11 @@
 // https://batterybro.com/blogs/18650-wholesale-battery-reviews/18852515-when-to-recycle-18650-batteries-and-how-to-start-a-collection-center-in-your-vape-shop
 // Discharge voltage: 2.5 volt + .1 for personal safety
 #ifndef USERMOD_BATTERY_MIN_VOLTAGE
-  #define USERMOD_BATTERY_MIN_VOLTAGE 2.6
+  #define USERMOD_BATTERY_MIN_VOLTAGE 2.6f
 #endif
 
 #ifndef USERMOD_BATTERY_MAX_VOLTAGE
-  #define USERMOD_BATTERY_MAX_VOLTAGE 4.2
+  #define USERMOD_BATTERY_MAX_VOLTAGE 4.2f
 #endif
 
 class UsermodBatteryBasic : public Usermod 

wled00/wled_math.h

@@ -80,36 +80,41 @@ float asin_t(float x) {
   return res;
 }
 
-//https://stackoverflow.com/a/42542593
+// declare a template with no implementation, and only one specialization
-#define A 0.0776509570923569
+// this allows hiding the constants, while ensuring ODR causes optimizations
-#define B -0.287434475393028
+// to still apply.  (Fixes issues with conflicting 3rd party #define's)
-#define C ((HALF_PI/2) - A - B)
+template <typename T> T atan_t(T x);
-
+template<>
-//polynominal factors for approximation between 1 and 5
-#define C0 0.089494f
-#define C1 0.974207f
-#define C2 -0.326175f
-#define C3 0.05375f
-#define C4 -0.003445f
-
 float atan_t(float x) {
-  bool neg = (x < 0);
+  //For A/B/C, see https://stackoverflow.com/a/42542593
+  static const double A { 0.0776509570923569 };
+  static const double B { -0.287434475393028 };
+  static const double C { ((HALF_PI/2) - A - B) };
+  // polynominal factors for approximation between 1 and 5
+  static const float C0 {  0.089494f };
+  static const float C1 {  0.974207f };
+  static const float C2 { -0.326175f };
+  static const float C3 {  0.05375f  };
+  static const float C4 { -0.003445f };
+
   #ifdef WLED_DEBUG_MATH
   float xinput = x;
   #endif
+  bool neg = (x < 0);
   x = std::abs(x);
   float res;
-  if (x > 5.0f) { //atan(x) converges to pi/2 - (1/x) for large values
+  if (x > 5.0f) { // atan(x) converges to pi/2 - (1/x) for large values
     res = HALF_PI - (1.0f/x);
-  }
+  } else if (x > 1.0f) { //1 < x < 5
-  else if (x > 1.0f) { //1 < x < 5
     float xx = x * x;
     res = (C4*xx*xx)+(C3*xx*x)+(C2*xx)+(C1*x)+C0;
-  } else { //this approximation is only for x <= 1
+  } else { // this approximation is only for x <= 1
     float xx = x * x;
     res = ((A*xx + B)*xx + C)*x;
   }
-  if (neg) res = -res;
+  if (neg) {
+    res = -res;
+  }
   #ifdef WLED_DEBUG_MATH
   Serial.printf("atan,%f,%f,%f\n",xinput,res,atan(xinput));
   #endif

wled00/wled_serial.cpp

@@ -46,8 +46,6 @@ void handleSerial()
   static byte red   = 0x00;
   static byte green = 0x00;
 
-  uint16_t nBytes = 0;
-  
   while (Serial.available() > 0)
   {
     yield();