Implement eeprom stored persistent histogram

fantemp/eeprom

@@ -1 +1 @@
-Subproject commit 33a4d55f03451f487ace046a6f2328351fda69ee
+Subproject commit 3bcba0a1919906d7cb358d3d8185a064bc1aa705

fantemp/statistics.cpp

@@ -8,59 +8,95 @@
 #include "clock.hpp"
 #include "controller.hpp"
 
-uint64_t Statistics::m_lastTempSave = 0;
+uint64_t Statistics::m_lastTemperatureWriteback = 0;
-double Statistics::m_minTemp;
+uint64_t Statistics::m_lastTemperatureSample = 0;
-double Statistics::m_maxTemp;
+uint32_t Statistics::m_temperatureHistogram[TEMPERATURE_RANGE];
 
 namespace {
 
 // Must be in translation unit and cannot be forward declared
-EEVAR(double, e_minTemp);
+EEARRAY(uint32_t, e_temperatureHistogram, 100);
-EEVAR(double, e_maxTemp);
 
 // Could be declared in every function that uses it, but that would be code duplication
-Eeprom<e_minTemp, true> g_eepMinTemp;
+EepromArray<e_temperatureHistogram, EEARRAY_SIZE(e_temperatureHistogram), true> g_eepTemperatureHistogram;
-Eeprom<e_maxTemp, true> g_eepMaxTemp;
 
 } // namespace
 
 void Statistics::init()
 {
-	m_minTemp = getMinTemp();
+	for (uint8_t i = 0; i < g_eepTemperatureHistogram.size(); ++i) {
-	m_maxTemp = getMaxTemp();
+		m_temperatureHistogram[i] = g_eepTemperatureHistogram[i];
-
+		using temperature_t = type::decay_t<decltype(m_temperatureHistogram[0])>;
-	if (isnan(m_minTemp)) {
+		if (m_temperatureHistogram[i] == type::numeric_limits<temperature_t>::max()) {
-		m_minTemp = type::numeric_limits<double>::max();
+			m_temperatureHistogram[i] = 0;
-	}
+		}
-	if (isnan(m_maxTemp)) {
-		m_maxTemp = type::numeric_limits<double>::lowest();
 	}
 }
 
 void Statistics::callback()
 {
 	if (Controller::m_dataAvailable) {
-		if (Controller::m_temperature < m_minTemp) {
+		if (clk::millis() >= m_lastTemperatureSample + TEMPERATURE_SAMPLE_DELAY) {
-			m_minTemp = Controller::m_temperature;
+			const auto temperature = clampTemperature(static_cast<int8_t>(round(Controller::m_temperature)));
-		}
+			++m_temperatureHistogram[temperature];
-		if (Controller::m_temperature > m_maxTemp) {
+			m_lastTemperatureSample = clk::millis();
-			m_maxTemp = Controller::m_temperature;
 		}
 
-		if (clk::millis() >= m_lastTempSave + TEMP_SAVE_DELAY) {
+		if (clk::millis() >= m_lastTemperatureWriteback + TEMPERATURE_WRITEBACK_DELAY) {
-			g_eepMinTemp = m_minTemp;
+			writeTemperatureHistogram();
-			g_eepMaxTemp = m_maxTemp;
+			m_lastTemperatureWriteback = clk::millis();
-			m_lastTempSave = clk::millis();
 		}
 	}
 }
 
-double Statistics::getMinTemp()
+uint8_t Statistics::getMinTemp()
 {
-	return g_eepMinTemp;
+	for (uint8_t i = 0; i < TEMPERATURE_RANGE; ++i) {
+		if (m_temperatureHistogram[i] > 0)
+			return i;
+	}
+
+	return TEMPERATURE_RANGE;
 }
 
-double Statistics::getMaxTemp()
+uint8_t Statistics::getMaxTemp()
 {
-	return g_eepMaxTemp;
+	for (int8_t i = TEMPERATURE_RANGE - 1; i >= 0; --i) {
+		if (m_temperatureHistogram[i] > 0)
+			return i;
+	}
+
+	return TEMPERATURE_RANGE;
+}
+
+uint32_t Statistics::getMaximumHistogramSamples()
+{
+	uint32_t max = 1; // Avoid division by zero
+	for (uint8_t i = 0; i < TEMPERATURE_RANGE; ++i) {
+		if (m_temperatureHistogram[i] > max) {
+			max = m_temperatureHistogram[i];
+		}
+	}
+	return max;
+}
+
+uint8_t Statistics::getHistogram(const int8_t &temperature, const uint32_t &normalizationFactor)
+{
+	return static_cast<uint8_t>(m_temperatureHistogram[clampTemperature(temperature)] / normalizationFactor);
+}
+
+uint8_t Statistics::clampTemperature(const int8_t &temperature)
+{
+	if (temperature < 0)
+		return 0;
+	if (temperature >= TEMPERATURE_RANGE)
+		return TEMPERATURE_RANGE - 1;
+	return static_cast<uint8_t>(temperature);
+}
+
+void Statistics::writeTemperatureHistogram()
+{
+	for (uint8_t i = 0; i < g_eepTemperatureHistogram.size(); ++i) {
+		g_eepTemperatureHistogram[i] = m_temperatureHistogram[i];
+	}
 }

fantemp/statistics.hpp

@@ -7,14 +7,21 @@ class Statistics {
 	static void init();
 	static void callback();
 
-	static double getMinTemp();
+	static uint8_t getMinTemp();
-	static double getMaxTemp();
+	static uint8_t getMaxTemp();
+
+	static uint32_t getMaximumHistogramSamples();
+	static uint8_t getHistogram(const int8_t &temperature, const uint32_t &normalizationFactor);
 
   private:
-	static constexpr auto TEMP_SAVE_DELAY = 60000;
+	static constexpr auto TEMPERATURE_WRITEBACK_DELAY = 1'800'000;
+	static constexpr auto TEMPERATURE_SAMPLE_DELAY = 1'000;
+	static constexpr auto TEMPERATURE_RANGE = 100;
 
-	static uint64_t m_lastTempSave;
+	static uint64_t m_lastTemperatureWriteback;
+	static uint64_t m_lastTemperatureSample;
+	static uint32_t m_temperatureHistogram[TEMPERATURE_RANGE];
 
-	static double m_minTemp;
+	static uint8_t clampTemperature(const int8_t &temperature);
-	static double m_maxTemp;
+	static void writeTemperatureHistogram();
 };

fantemp/terminal.hpp

@@ -22,9 +22,10 @@ GF(MONITOR_CMD, "monitor");
 GF(BOOTLOADER_CMD, "bootloader");
 GF(UPTIME_CMD, "uptime");
 GF(STATISTICS_CMD, "statistics");
+GF(HISTOGRAM_CMD, "histogram");
 
 GF(VERSION_CMD, "version");
-GF(VERSION, "1.4");
+GF(VERSION, "1.5");
 
 static inline bool substringEquals(const char *str, const ::detail::FlashString *flashStr, const size_t &size)
 {
@@ -146,6 +147,8 @@ class Terminal {
 					printUptime();
 				} else if (substringEquals(m_inputBuffer, detail::STATISTICS_CMD, m_inputSize)) {
 					printStatistics();
+				} else if (substringEquals(m_inputBuffer, detail::HISTOGRAM_CMD, m_inputSize)) {
+					printHistogram();
 				} else if (substringEquals(m_inputBuffer, detail::VERSION_CMD, m_inputSize)) {
 					printVersion();
 				} else {
@@ -175,6 +178,7 @@ class Terminal {
 		m_serial << detail::BOOTLOADER_CMD << F(" .: enters the bootloader after 3 seconds") << detail::ENDL;
 		m_serial << detail::UPTIME_CMD << F(" .....: show system uptime") << detail::ENDL;
 		m_serial << detail::STATISTICS_CMD << F(" .: Print overall statistics like min and max temp") << detail::ENDL;
+		m_serial << detail::HISTOGRAM_CMD << F(" ..: Prints a histogram of the temperature") << detail::ENDL;
 		m_serial << detail::VERSION_CMD << F(" ....: displays firmware version") << detail::ENDL;
 	}
 
@@ -202,7 +206,7 @@ class Terminal {
 			m_serial.template txNumber<uint8_t, 10, 3, ' '>(Controller::mapTemperature(i));
 			m_serial << F("%\t");
 			for (uint8_t s = 0; s < Controller::mapTemperature(i); ++s) {
-				m_serial << "#";
+				m_serial << '#';
 			}
 			m_serial << detail::ENDL;
 		}
@@ -239,12 +243,23 @@ class Terminal {
 
 	static void printStatistics()
 	{
-		char floatBuffer[16];
+		m_serial << F("Minimum temperature .: ") << Statistics::getMinTemp() << F(" C") << detail::ENDL;
+		m_serial << F("Maximum temperature .: ") << Statistics::getMaxTemp() << F(" C") << detail::ENDL;
+	}
 
-		sprintf(floatBuffer, "%.2f", Statistics::getMinTemp());
+	static void printHistogram()
-		m_serial << F("Minimum temperature .: ") << floatBuffer << F(" C") << detail::ENDL;
+	{
-		sprintf(floatBuffer, "%.2f", Statistics::getMaxTemp());
+		auto normalizationFactor = Statistics::getMaximumHistogramSamples();
-		m_serial << F("Maximum temperature .: ") << floatBuffer << F(" C") << detail::ENDL;
+		normalizationFactor = (normalizationFactor / 100 > 1) ? (normalizationFactor / 100) : 1;
+
+		for (uint8_t t = 10; t <= 60; ++t) {
+			m_serial.template txNumber<uint8_t, 10, 2>(t);
+			m_serial << F(" C\t");
+			for (uint8_t i = 0; i < Statistics::getHistogram(t, normalizationFactor); ++i) {
+				m_serial << '#';
+			}
+			m_serial << detail::ENDL;
+		}
 	}
 
 	static void printVersion()