making some parameters const, plus minor improvements

* changed some parameters to "pointer to const", so compiler can better optimize code size and performance -  because data behind a const pointer will never be modified by the called function.
* made setPixelColor `const`

* fixed a few potentially uninitialized local vars (the may have random values if not initialized)

* avoid shadowing "state" in handleSerial()
* plus a few very minor improvements

Author: softhack007

wled00/FX.cpp

@@ -2363,7 +2363,7 @@ static const char _data_FX_MODE_LAKE[] PROGMEM = "Lake@!;Fx;!";
 // send a meteor from begining to to the end of the strip with a trail that randomly decays.
 // adapted from https://www.tweaking4all.com/hardware/arduino/adruino-led-strip-effects/#LEDStripEffectMeteorRain
 uint16_t mode_meteor() {
-  if (SEGLEN == 1) return mode_static();
+  if (SEGLEN <= 1) return mode_static();
   if (!SEGENV.allocateData(SEGLEN)) return mode_static(); //allocation failed
   const bool meteorSmooth = SEGMENT.check3;
   byte* trail = SEGENV.data;
@@ -2531,7 +2531,7 @@ static uint16_t ripple_base(uint8_t blurAmount = 0) {
 
 
 uint16_t mode_ripple(void) {
-  if (SEGLEN == 1) return mode_static();
+  if (SEGLEN <= 1) return mode_static();
   if(SEGMENT.custom1 || SEGMENT.check2) // blur or overlay
     SEGMENT.fade_out(250);
   else
@@ -2543,7 +2543,7 @@ static const char _data_FX_MODE_RIPPLE[] PROGMEM = "Ripple@!,Wave #,Blur,,,,Over
 
 
 uint16_t mode_ripple_rainbow(void) {
-  if (SEGLEN == 1) return mode_static();
+  if (SEGLEN <= 1) return mode_static();
   if (SEGENV.call ==0) {
     SEGENV.aux0 = hw_random8();
     SEGENV.aux1 = hw_random8();
@@ -3984,7 +3984,7 @@ static const char _data_FX_MODE_HEARTBEAT[] PROGMEM = "Heartbeat@!,!;!,!;!;01;m1
 // Modified for WLED, based on https://github.com/FastLED/FastLED/blob/master/examples/Pacifica/Pacifica.ino
 //
 // Add one layer of waves into the led array
-static CRGB pacifica_one_layer(uint16_t i, CRGBPalette16& p, uint16_t cistart, uint16_t wavescale, uint8_t bri, uint16_t ioff)
+static CRGB pacifica_one_layer(uint16_t i, const CRGBPalette16& p, uint16_t cistart, uint16_t wavescale, uint8_t bri, uint16_t ioff)
 {
   unsigned ci = cistart;
   unsigned waveangle = ioff;

wled00/FX.h

@@ -460,7 +460,7 @@ typedef struct Segment {
       {}
     } *_t;
 
-    [[gnu::hot]] void _setPixelColorXY_raw(int& x, int& y, uint32_t& col) const; // set pixel without mapping (internal use only)
+    [[gnu::hot]] void _setPixelColorXY_raw(const int& x, const int& y, uint32_t& col) const; // set pixel without mapping (internal use only)
 
   public:
 
@@ -588,7 +588,7 @@ typedef struct Segment {
     inline void handleTransition() { updateTransitionProgress(); if (progress() == 0xFFFFU) stopTransition(); }
     #ifndef WLED_DISABLE_MODE_BLEND
     void     swapSegenv(tmpsegd_t &tmpSegD);    // copies segment data into specifed buffer, if buffer is not a transition buffer, segment data is overwritten from transition buffer
-    void     restoreSegenv(tmpsegd_t &tmpSegD); // restores segment data from buffer, if buffer is not transition buffer, changed values are copied to transition buffer
+    void     restoreSegenv(const tmpsegd_t &tmpSegD); // restores segment data from buffer, if buffer is not transition buffer, changed values are copied to transition buffer
     #endif
     [[gnu::hot]] void updateTransitionProgress();            // set current progression of transition
     inline uint16_t progress() const { return _transitionprogress; };  // transition progression between 0-65535
@@ -643,11 +643,11 @@ typedef struct Segment {
     }
   #ifndef WLED_DISABLE_2D
     [[gnu::hot]] uint16_t XY(int x, int y) const;      // support function to get relative index within segment
-    [[gnu::hot]] void setPixelColorXY(int x, int y, uint32_t c); // set relative pixel within segment with color
-    inline void setPixelColorXY(unsigned x, unsigned y, uint32_t c)               { setPixelColorXY(int(x), int(y), c); }
-    inline void setPixelColorXY(int x, int y, byte r, byte g, byte b, byte w = 0) { setPixelColorXY(x, y, RGBW32(r,g,b,w)); }
-    inline void setPixelColorXY(int x, int y, CRGB c)                             { setPixelColorXY(x, y, RGBW32(c.r,c.g,c.b,0)); }
-    inline void setPixelColorXY(unsigned x, unsigned y, CRGB c)                   { setPixelColorXY(int(x), int(y), RGBW32(c.r,c.g,c.b,0)); }
+    [[gnu::hot]] void setPixelColorXY(int x, int y, uint32_t c) const; // set relative pixel within segment with color
+    inline void setPixelColorXY(unsigned x, unsigned y, uint32_t c) const               { setPixelColorXY(int(x), int(y), c); }
+    inline void setPixelColorXY(int x, int y, byte r, byte g, byte b, byte w = 0) const { setPixelColorXY(x, y, RGBW32(r,g,b,w)); }
+    inline void setPixelColorXY(int x, int y, CRGB c) const                             { setPixelColorXY(x, y, RGBW32(c.r,c.g,c.b,0)); }
+    inline void setPixelColorXY(unsigned x, unsigned y, CRGB c) const                   { setPixelColorXY(int(x), int(y), RGBW32(c.r,c.g,c.b,0)); }
     #ifdef WLED_USE_AA_PIXELS
     void setPixelColorXY(float x, float y, uint32_t c, bool aa = true);
     inline void setPixelColorXY(float x, float y, byte r, byte g, byte b, byte w = 0, bool aa = true) { setPixelColorXY(x, y, RGBW32(r,g,b,w), aa); }

wled00/FX_2Dfcn.cpp

@@ -154,7 +154,7 @@ uint16_t IRAM_ATTR_YN Segment::XY(int x, int y) const
 }
 
 // raw setColor function without checks (checks are done in setPixelColorXY())
-void IRAM_ATTR_YN Segment::_setPixelColorXY_raw(int& x, int& y, uint32_t& col) const
+void IRAM_ATTR_YN Segment::_setPixelColorXY_raw(const int& x, const int& y, uint32_t& col) const
 {
   const int baseX = start + x;
   const int baseY = startY + y;
@@ -179,7 +179,7 @@ void IRAM_ATTR_YN Segment::_setPixelColorXY_raw(int& x, int& y, uint32_t& col) c
   }
 }
 
-void IRAM_ATTR_YN Segment::setPixelColorXY(int x, int y, uint32_t col)
+void IRAM_ATTR_YN Segment::setPixelColorXY(int x, int y, uint32_t col) const
 {
   if (!isActive()) return; // not active
 
@@ -276,8 +276,8 @@ void Segment::blur2D(uint8_t blur_x, uint8_t blur_y, bool smear) {
   if (!isActive()) return; // not active
   const unsigned cols = vWidth();
   const unsigned rows = vHeight();
-  uint32_t lastnew;
-  uint32_t last;
+  uint32_t lastnew = BLACK;
+  uint32_t last = BLACK;
   if (blur_x) {
     const uint8_t keepx = smear ? 255 : 255 - blur_x;
     const uint8_t seepx = blur_x >> 1;

wled00/FX_fcn.cpp

@@ -347,7 +347,7 @@ void Segment::swapSegenv(tmpsegd_t &tmpSeg) {
   }
 }
 
-void Segment::restoreSegenv(tmpsegd_t &tmpSeg) {
+void Segment::restoreSegenv(const tmpsegd_t &tmpSeg) {
   //DEBUG_PRINTF_P(PSTR("--  Restoring temp seg: %p->(%p) [%d->%p]\n"), &tmpSeg, this, _dataLen, data);
   if (_t && &(_t->_segT) != &tmpSeg) {
     // update possibly changed variables to keep old effect running correctly
@@ -1134,8 +1134,8 @@ void Segment::blur(uint8_t blur_amount, bool smear) {
   uint8_t seep = blur_amount >> 1;
   unsigned vlength = vLength();
   uint32_t carryover = BLACK;
-  uint32_t lastnew;
-  uint32_t last;
+  uint32_t lastnew = BLACK;
+  uint32_t last = BLACK;
   uint32_t curnew = BLACK;
   for (unsigned i = 0; i < vlength; i++) {
     uint32_t cur = getPixelColor(i);

wled00/bus_manager.cpp

@@ -27,7 +27,7 @@ extern bool cctICused;
 uint32_t colorBalanceFromKelvin(uint16_t kelvin, uint32_t rgb);
 
 //udp.cpp
-uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, byte *buffer, uint8_t bri=255, bool isRGBW=false);
+uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, const uint8_t* buffer, uint8_t bri=255, bool isRGBW=false);
 
 // enable additional debug output
 #if defined(WLED_DEBUG_HOST)
@@ -121,7 +121,7 @@ uint8_t *Bus::allocateData(size_t size) {
 }
 
 
-BusDigital::BusDigital(BusConfig &bc, uint8_t nr, const ColorOrderMap &com)
+BusDigital::BusDigital(const BusConfig &bc, uint8_t nr, const ColorOrderMap &com)
 : Bus(bc.type, bc.start, bc.autoWhite, bc.count, bc.reversed, (bc.refreshReq || bc.type == TYPE_TM1814))
 , _skip(bc.skipAmount) //sacrificial pixels
 , _colorOrder(bc.colorOrder)
@@ -448,7 +448,7 @@ void BusDigital::cleanup() {
   #endif
 #endif
 
-BusPwm::BusPwm(BusConfig &bc)
+BusPwm::BusPwm(const BusConfig &bc)
 : Bus(bc.type, bc.start, bc.autoWhite, 1, bc.reversed, bc.refreshReq) // hijack Off refresh flag to indicate usage of dithering
 {
   if (!isPWM(bc.type)) return;
@@ -646,7 +646,7 @@ void BusPwm::deallocatePins() {
 }
 
 
-BusOnOff::BusOnOff(BusConfig &bc)
+BusOnOff::BusOnOff(const BusConfig &bc)
 : Bus(bc.type, bc.start, bc.autoWhite, 1, bc.reversed)
 , _onoffdata(0)
 {
@@ -699,7 +699,7 @@ std::vector<LEDType> BusOnOff::getLEDTypes() {
   };
 }
 
-BusNetwork::BusNetwork(BusConfig &bc)
+BusNetwork::BusNetwork(const BusConfig &bc)
 : Bus(bc.type, bc.start, bc.autoWhite, bc.count)
 , _broadcastLock(false)
 {
@@ -778,7 +778,7 @@ void BusNetwork::cleanup() {
 
 
 //utility to get the approx. memory usage of a given BusConfig
-uint32_t BusManager::memUsage(BusConfig &bc) {
+uint32_t BusManager::memUsage(const BusConfig &bc) {
   if (Bus::isOnOff(bc.type) || Bus::isPWM(bc.type)) return OUTPUT_MAX_PINS;
 
   unsigned len = bc.count + bc.skipAmount;
@@ -803,7 +803,7 @@ uint32_t BusManager::memUsage(unsigned maxChannels, unsigned maxCount, unsigned
   return (maxChannels * maxCount * minBuses * multiplier);
 }
 
-int BusManager::add(BusConfig &bc) {
+int BusManager::add(const BusConfig &bc) {
   if (getNumBusses() - getNumVirtualBusses() >= WLED_MAX_BUSSES) return -1;
   if (Bus::isVirtual(bc.type)) {
     busses[numBusses] = new BusNetwork(bc);

wled00/bus_manager.h

@@ -198,7 +198,7 @@ class Bus {
 
 class BusDigital : public Bus {
   public:
-    BusDigital(BusConfig &bc, uint8_t nr, const ColorOrderMap &com);
+    BusDigital(const BusConfig &bc, uint8_t nr, const ColorOrderMap &com);
     ~BusDigital() { cleanup(); }
 
     void show() override;
@@ -250,7 +250,7 @@ class BusDigital : public Bus {
 
 class BusPwm : public Bus {
   public:
-    BusPwm(BusConfig &bc);
+    BusPwm(const BusConfig &bc);
     ~BusPwm() { cleanup(); }
 
     void setPixelColor(unsigned pix, uint32_t c) override;
@@ -277,7 +277,7 @@ class BusPwm : public Bus {
 
 class BusOnOff : public Bus {
   public:
-    BusOnOff(BusConfig &bc);
+    BusOnOff(const BusConfig &bc);
     ~BusOnOff() { cleanup(); }
 
     void setPixelColor(unsigned pix, uint32_t c) override;
@@ -296,7 +296,7 @@ class BusOnOff : public Bus {
 
 class BusNetwork : public Bus {
   public:
-    BusNetwork(BusConfig &bc);
+    BusNetwork(const BusConfig &bc);
     ~BusNetwork() { cleanup(); }
 
     bool canShow() const override  { return !_broadcastLock; } // this should be a return value from UDP routine if it is still sending data out
@@ -379,12 +379,12 @@ class BusManager {
     BusManager() {};
 
     //utility to get the approx. memory usage of a given BusConfig
-    static uint32_t memUsage(BusConfig &bc);
+    static uint32_t memUsage(const BusConfig &bc);
     static uint32_t memUsage(unsigned channels, unsigned count, unsigned buses = 1);
     static uint16_t currentMilliamps() { return _milliAmpsUsed + MA_FOR_ESP; }
     static uint16_t ablMilliampsMax()  { return _milliAmpsMax; }
 
-    static int add(BusConfig &bc);
+    static int add(const BusConfig &bc);
     static void useParallelOutput(); // workaround for inaccessible PolyBus
 
     //do not call this method from system context (network callback)

wled00/colors.cpp

@@ -122,7 +122,7 @@ void setRandomColor(byte* rgb)
  * generates a random palette based on harmonic color theory
  * takes a base palette as the input, it will choose one color of the base palette and keep it
  */
-CRGBPalette16 generateHarmonicRandomPalette(CRGBPalette16 &basepalette)
+CRGBPalette16 generateHarmonicRandomPalette(const CRGBPalette16 &basepalette)
 {
   CHSV palettecolors[4]; // array of colors for the new palette
   uint8_t keepcolorposition = hw_random8(4); // color position of current random palette to keep
@@ -391,7 +391,7 @@ void colorXYtoRGB(float x, float y, byte* rgb) //coordinates to rgb (https://www
   rgb[2] = byte(255.0f*b);
 }
 
-void colorRGBtoXY(byte* rgb, float* xy) //rgb to coordinates (https://www.developers.meethue.com/documentation/color-conversions-rgb-xy)
+void colorRGBtoXY(const byte* rgb, float* xy) //rgb to coordinates (https://www.developers.meethue.com/documentation/color-conversions-rgb-xy)
 {
   float X = rgb[0] * 0.664511f + rgb[1] * 0.154324f + rgb[2] * 0.162028f;
   float Y = rgb[0] * 0.283881f + rgb[1] * 0.668433f + rgb[2] * 0.047685f;
@@ -402,7 +402,7 @@ void colorRGBtoXY(byte* rgb, float* xy) //rgb to coordinates (https://www.develo
 #endif // WLED_DISABLE_HUESYNC
 
 //RRGGBB / WWRRGGBB order for hex
-void colorFromDecOrHexString(byte* rgb, char* in)
+void colorFromDecOrHexString(byte* rgb, const char* in)
 {
   if (in[0] == 0) return;
   char first = in[0];

wled00/fcn_declare.h

@@ -166,7 +166,7 @@ inline uint32_t color_blend16(uint32_t c1, uint32_t c2, uint16_t b) { return col
 [[gnu::hot]] uint32_t color_add(uint32_t, uint32_t, bool preserveCR = false);
 [[gnu::hot]] uint32_t color_fade(uint32_t c1, uint8_t amount, bool video=false);
 [[gnu::hot]] uint32_t ColorFromPaletteWLED(const CRGBPalette16 &pal, unsigned index, uint8_t brightness = (uint8_t)255U, TBlendType blendType = LINEARBLEND);
-CRGBPalette16 generateHarmonicRandomPalette(CRGBPalette16 &basepalette);
+CRGBPalette16 generateHarmonicRandomPalette(const CRGBPalette16 &basepalette);
 CRGBPalette16 generateRandomPalette();
 inline uint32_t colorFromRgbw(byte* rgbw) { return uint32_t((byte(rgbw[3]) << 24) | (byte(rgbw[0]) << 16) | (byte(rgbw[1]) << 8) | (byte(rgbw[2]))); }
 void hsv2rgb(const CHSV32& hsv, uint32_t& rgb);
@@ -177,7 +177,7 @@ void colorKtoRGB(uint16_t kelvin, byte* rgb);
 void colorCTtoRGB(uint16_t mired, byte* rgb); //white spectrum to rgb
 void colorXYtoRGB(float x, float y, byte* rgb); // only defined if huesync disabled TODO
 void colorRGBtoXY(byte* rgb, float* xy); // only defined if huesync disabled TODO
-void colorFromDecOrHexString(byte* rgb, char* in);
+void colorFromDecOrHexString(byte* rgb, const char* in);
 bool colorFromHexString(byte* rgb, const char* in);
 uint32_t colorBalanceFromKelvin(uint16_t kelvin, uint32_t rgb);
 uint16_t approximateKelvinFromRGB(uint32_t rgb);
@@ -200,14 +200,14 @@ void sendArtnetPollReply(ArtPollReply* reply, IPAddress ipAddress, uint16_t port
 
 //file.cpp
 bool handleFileRead(AsyncWebServerRequest*, String path);
-bool writeObjectToFileUsingId(const char* file, uint16_t id, JsonDocument* content);
-bool writeObjectToFile(const char* file, const char* key, JsonDocument* content);
+bool writeObjectToFileUsingId(const char* file, uint16_t id, const JsonDocument* content);
+bool writeObjectToFile(const char* file, const char* key, const JsonDocument* content);
 bool readObjectFromFileUsingId(const char* file, uint16_t id, JsonDocument* dest);
 bool readObjectFromFile(const char* file, const char* key, JsonDocument* dest);
 void updateFSInfo();
 void closeFile();
-inline bool writeObjectToFileUsingId(const String &file, uint16_t id, JsonDocument* content) { return writeObjectToFileUsingId(file.c_str(), id, content); };
-inline bool writeObjectToFile(const String &file, const char* key, JsonDocument* content) { return writeObjectToFile(file.c_str(), key, content); };
+inline bool writeObjectToFileUsingId(const String &file, uint16_t id, const JsonDocument* content) { return writeObjectToFileUsingId(file.c_str(), id, content); };
+inline bool writeObjectToFile(const String &file, const char* key, const JsonDocument* content) { return writeObjectToFile(file.c_str(), key, content); };
 inline bool readObjectFromFileUsingId(const String &file, uint16_t id, JsonDocument* dest) { return readObjectFromFileUsingId(file.c_str(), id, dest); };
 inline bool readObjectFromFile(const String &file, const char* key, JsonDocument* dest) { return readObjectFromFile(file.c_str(), key, dest); };
 
@@ -248,7 +248,7 @@ void handleIR();
 
 bool deserializeSegment(JsonObject elem, byte it, byte presetId = 0);
 bool deserializeState(JsonObject root, byte callMode = CALL_MODE_DIRECT_CHANGE, byte presetId = 0);
-void serializeSegment(JsonObject& root, Segment& seg, byte id, bool forPreset = false, bool segmentBounds = true);
+void serializeSegment(const JsonObject& root, const Segment& seg, byte id, bool forPreset = false, bool segmentBounds = true);
 void serializeState(JsonObject root, bool forPreset = false, bool includeBri = true, bool segmentBounds = true, bool selectedSegmentsOnly = false);
 void serializeInfo(JsonObject root);
 void serializeModeNames(JsonArray root);
@@ -333,7 +333,7 @@ bool handleSet(AsyncWebServerRequest *request, const String& req, bool apply=tru
 
 //udp.cpp
 void notify(byte callMode, bool followUp=false);
-uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, uint8_t *buffer, uint8_t bri=255, bool isRGBW=false);
+uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, const uint8_t* buffer, uint8_t bri=255, bool isRGBW=false);
 void realtimeLock(uint32_t timeoutMs, byte md = REALTIME_MODE_GENERIC);
 void exitRealtime();
 void handleNotifications();

wled00/file.cpp

@@ -176,7 +176,7 @@ static void writeSpace(size_t l)
   if (knownLargestSpace < l) knownLargestSpace = l;
 }
 
-bool appendObjectToFile(const char* key, JsonDocument* content, uint32_t s, uint32_t contentLen = 0)
+bool appendObjectToFile(const char* key, const JsonDocument* content, uint32_t s, uint32_t contentLen = 0)
 {
   #ifdef WLED_DEBUG_FS
     DEBUGFS_PRINTLN(F("Append"));
@@ -255,14 +255,14 @@ bool appendObjectToFile(const char* key, JsonDocument* content, uint32_t s, uint
   return true;
 }
 
-bool writeObjectToFileUsingId(const char* file, uint16_t id, JsonDocument* content)
+bool writeObjectToFileUsingId(const char* file, uint16_t id, const JsonDocument* content)
 {
   char objKey[10];
   sprintf(objKey, "\"%d\":", id);
   return writeObjectToFile(file, objKey, content);
 }
 
-bool writeObjectToFile(const char* file, const char* key, JsonDocument* content)
+bool writeObjectToFile(const char* file, const char* key, const JsonDocument* content)
 {
   uint32_t s = 0; //timing
   #ifdef WLED_DEBUG_FS

wled00/json.cpp

@@ -493,7 +493,7 @@ bool deserializeState(JsonObject root, byte callMode, byte presetId)
   return stateResponse;
 }
 
-void serializeSegment(JsonObject& root, Segment& seg, byte id, bool forPreset, bool segmentBounds)
+void serializeSegment(const JsonObject& root, const Segment& seg, byte id, bool forPreset, bool segmentBounds)
 {
   root["id"] = id;
   if (segmentBounds) {

wled00/ntp.cpp

@@ -224,7 +224,7 @@ void sendNTPPacket()
   ntpUdp.endPacket();
 }
 
-static bool isValidNtpResponse(byte * ntpPacket) {
+static bool isValidNtpResponse(const byte* ntpPacket) {
   // Perform a few validity checks on the packet
   //   based on https://github.com/taranais/NTPClient/blob/master/NTPClient.cpp
   if((ntpPacket[0] & 0b11000000) == 0b11000000) return false; //reject LI=UNSYNC

wled00/set.cpp

@@ -990,18 +990,18 @@ bool handleSet(AsyncWebServerRequest *request, const String& req, bool apply)
   //set color from HEX or 32bit DEC
   pos = req.indexOf(F("CL="));
   if (pos > 0) {
-    colorFromDecOrHexString(colIn, (char*)req.substring(pos + 3).c_str());
+    colorFromDecOrHexString(colIn, (const char*)req.substring(pos + 3).c_str());
     col0Changed = true;
   }
   pos = req.indexOf(F("C2="));
   if (pos > 0) {
-    colorFromDecOrHexString(colInSec, (char*)req.substring(pos + 3).c_str());
+    colorFromDecOrHexString(colInSec, (const char*)req.substring(pos + 3).c_str());
     col1Changed = true;
   }
   pos = req.indexOf(F("C3="));
   if (pos > 0) {
     byte tmpCol[4];
-    colorFromDecOrHexString(tmpCol, (char*)req.substring(pos + 3).c_str());
+    colorFromDecOrHexString(tmpCol, (const char*)req.substring(pos + 3).c_str());
     col2 = RGBW32(tmpCol[0], tmpCol[1], tmpCol[2], tmpCol[3]);
     selseg.setColor(2, col2); // defined above (SS= or main)
     col2Changed = true;