1 files changed, 85 insertions, 0 deletions
diff --git a/src/ipa/libipa/pwl.h b/src/ipa/libipa/pwl.h
new file mode 100644
index 00000000..d4ec9f4f
--- /dev/null
+++ b/src/ipa/libipa/pwl.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi Ltd
+ *
+ * Piecewise linear functions interface
+ */
+#pragma once
+
+#include <algorithm>
+#include <functional>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "vector.h"
+
+namespace libcamera {
+
+namespace ipa {
+
+class Pwl
+{
+public:
+	using Point = Vector<double, 2>;
+
+	struct Interval {
+		Interval(double _start, double _end)
+			: start(_start), end(_end) {}
+
+		bool contains(double value)
+		{
+			return value >= start && value <= end;
+		}
+
+		double clamp(double value)
+		{
+			return std::clamp(value, start, end);
+		}
+
+		double length() const { return end - start; }
+
+		double start, end;
+	};
+
+	Pwl();
+	Pwl(const std::vector<Point> &points);
+	Pwl(std::vector<Point> &&points);
+
+	void append(double x, double y, double eps = 1e-6);
+
+	bool empty() const { return points_.empty(); }
+	size_t size() const { return points_.size(); }
+
+	Interval domain() const;
+	Interval range() const;
+
+	double eval(double x, int *span = nullptr,
+		    bool updateSpan = true) const;
+
+	std::pair<Pwl, bool> inverse(double eps = 1e-6) const;
+	Pwl compose(const Pwl &other, double eps = 1e-6) const;
+
+	void map(std::function<void(double x, double y)> f) const;
+
+	static Pwl
+	combine(const Pwl &pwl0, const Pwl &pwl1,
+		std::function<double(double x, double y0, double y1)> f,
+		double eps = 1e-6);
+
+	Pwl &operator*=(double d);
+
+	std::string toString() const;
+
+private:
+	static void map2(const Pwl &pwl0, const Pwl &pwl1,
+			 std::function<void(double x, double y0, double y1)> f);
+	void prepend(double x, double y, double eps = 1e-6);
+	int findSpan(double x, int span) const;
+
+	std::vector<Point> points_;
+};
+
+} /* namespace ipa */
+
+} /* namespace libcamera */