added a fixed-frequency interpolator

tests/math/TestFixedFrequencyInterpolator.cpp

@@ -0,0 +1,61 @@
+#ifdef WITH_TESTS
+
+#include <cmath>
+#include "../Tests.h"
+#include "../../math/FixedFrequencyInterpolator.h"
+#include <fstream>
+
+TEST(FixedFrequencyInterpolator, test) {
+
+	FixedFrequencyInterpolator<float> ffi(Timestamp::fromMS(10));
+
+	std::ofstream out("/tmp/test.dat");
+
+	std::vector<float> data;
+	auto callback = [&] (const Timestamp ts, const float val) {
+		out << ts.ms() << " " << val << "\n";
+		data.push_back(val);
+	};
+
+	float x = 10;
+
+	// output should be a straight line
+	ffi.add(Timestamp::fromMS(55), x*55, callback);
+	ffi.add(Timestamp::fromMS(93), x*93, callback);
+	ffi.add(Timestamp::fromMS(102), x*102, callback);
+	ffi.add(Timestamp::fromMS(134), x*134, callback);
+	ffi.add(Timestamp::fromMS(212), x*212, callback);
+	ffi.add(Timestamp::fromMS(214), x*214, callback);
+	ffi.add(Timestamp::fromMS(216), x*216, callback);
+	ffi.add(Timestamp::fromMS(219), x*219, callback);
+	ffi.add(Timestamp::fromMS(220), x*220, callback);
+	ffi.add(Timestamp::fromMS(240), x*240, callback);
+
+	out.close();
+
+	const float d = 0.001;
+	ASSERT_NEAR(data[0], x*60, d);
+	ASSERT_NEAR(data[1], x*70, d);
+	ASSERT_NEAR(data[2], x*80, d);
+	ASSERT_NEAR(data[3], x*90, d);
+	ASSERT_NEAR(data[4], x*100, d);
+	ASSERT_NEAR(data[5], x*110, d);
+	ASSERT_NEAR(data[6], x*120, d);
+	ASSERT_NEAR(data[7], x*130, d);
+	ASSERT_NEAR(data[8], x*140, d);
+	ASSERT_NEAR(data[9], x*150, d);
+	ASSERT_NEAR(data[10], x*160, d);
+	ASSERT_NEAR(data[11], x*170, d);
+	ASSERT_NEAR(data[12], x*180, d);
+	ASSERT_NEAR(data[13], x*190, d);
+	ASSERT_NEAR(data[14], x*200, d);
+	ASSERT_NEAR(data[15], x*210, d);
+	ASSERT_NEAR(data[16], x*220, d);
+	ASSERT_NEAR(data[17], x*230, d);
+	ASSERT_NEAR(data[18], x*240, d);
+
+}
+
+
+
+#endif