deadband for PPS #5420

only: just a test for now

unit_tests/tests/test_sticky_pps.cpp

@@ -0,0 +1,46 @@
+
+#include "pch.h"
+// todo: should we unify code with deadband.h?
+
+template <typename T>
+class StickyValue {
+public:
+	T get(T currentValue, T deadbandThreshold) {
+		// If we're within the deadband, be "sticky" with the previous value
+		T absError = absF(currentValue - m_lastValue);
+
+		if (std::is_same<T,float>::value) {
+			if (cisnan(currentValue))
+				return currentValue;
+			if (cisnan(m_lastValue))
+				m_lastValue = currentValue;
+		}
+
+		// use current value if there's enough error
+		if (absError > deadbandThreshold) {
+			m_lastValue = currentValue;
+		}
+
+		return m_lastValue;
+	}
+
+private:
+	T m_lastValue = 0;
+};
+
+
+TEST(Sticky, PPS) {
+	StickyValue<float> pps;
+
+	float threshold = 0.5;
+
+	EXPECT_EQ(1, pps.get(1, threshold));
+	EXPECT_EQ(1, pps.get(1.2, threshold));
+	EXPECT_EQ(1, pps.get(0.8, threshold));
+	EXPECT_NEAR(2.2, pps.get(2.2, threshold), EPS4D);
+
+	float expectedNaN = pps.get(NAN, threshold);
+	EXPECT_TRUE(cisnan(expectedNaN));
+
+	EXPECT_NEAR(33, pps.get(33, threshold), EPS4D);
+}

unit_tests/tests/tests.mk

@@ -79,6 +79,7 @@ TESTS_SRC_CPP = \
 	tests/test_accel_enrichment.cpp \
 	tests/test_gpiochip.cpp \
 	tests/test_deadband.cpp \
+	tests/test_sticky_pps.cpp \
 	tests/test_knock.cpp \
 	tests/test_lambda_monitor.cpp \
 	tests/sensor/basic_sensor.cpp \