libcamera: ipa: Raspberry Pi IPA

Initial implementation of the Raspberry Pi (BCM2835) libcamera IPA and
associated libraries.

All code is licensed under the BSD-2-Clause terms.
Copyright (c) 2019-2020 Raspberry Pi Trading Ltd.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 216 insertions, 0 deletions

diff --git a/src/ipa/raspberrypi/controller/pwl.cpp b/src/ipa/raspberrypi/controller/pwl.cpp
new file mode 100644
index 00000000..7e11d8f3
--- /dev/null
+++ b/src/ipa/raspberrypi/controller/pwl.cpp
@@ -0,0 +1,216 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2019, Raspberry Pi (Trading) Limited
+ *
+ * pwl.cpp - piecewise linear functions
+ */
+
+#include <cassert>
+#include <stdexcept>
+
+#include "pwl.hpp"
+
+using namespace RPi;
+
+void Pwl::Read(boost::property_tree::ptree const &params)
+{
+	for (auto it = params.begin(); it != params.end(); it++) {
+		double x = it->second.get_value<double>();
+		assert(it == params.begin() || x > points_.back().x);
+		it++;
+		double y = it->second.get_value<double>();
+		points_.push_back(Point(x, y));
+	}
+	assert(points_.size() >= 2);
+}
+
+void Pwl::Append(double x, double y, const double eps)
+{
+	if (points_.empty() || points_.back().x + eps < x)
+		points_.push_back(Point(x, y));
+}
+
+void Pwl::Prepend(double x, double y, const double eps)
+{
+	if (points_.empty() || points_.front().x - eps > x)
+		points_.insert(points_.begin(), Point(x, y));
+}
+
+Pwl::Interval Pwl::Domain() const
+{
+	return Interval(points_[0].x, points_[points_.size() - 1].x);
+}
+
+Pwl::Interval Pwl::Range() const
+{
+	double lo = points_[0].y, hi = lo;
+	for (auto &p : points_)
+		lo = std::min(lo, p.y), hi = std::max(hi, p.y);
+	return Interval(lo, hi);
+}
+
+bool Pwl::Empty() const
+{
+	return points_.empty();
+}
+
+double Pwl::Eval(double x, int *span_ptr, bool update_span) const
+{
+	int span = findSpan(x, span_ptr && *span_ptr != -1
+				       ? *span_ptr
+				       : points_.size() / 2 - 1);
+	if (span_ptr && update_span)
+		*span_ptr = span;
+	return points_[span].y +
+	       (x - points_[span].x) * (points_[span + 1].y - points_[span].y) /
+		       (points_[span + 1].x - points_[span].x);
+}
+
+int Pwl::findSpan(double x, int span) const
+{
+	// Pwls are generally small, so linear search may well be faster than
+	// binary, though could review this if large PWls start turning up.
+	int last_span = points_.size() - 2;
+	// some algorithms may call us with span pointing directly at the last
+	// control point
+	span = std::max(0, std::min(last_span, span));
+	while (span < last_span && x >= points_[span + 1].x)
+		span++;
+	while (span && x < points_[span].x)
+		span--;
+	return span;
+}
+
+Pwl::PerpType Pwl::Invert(Point const &xy, Point &perp, int &span,
+			  const double eps) const
+{
+	assert(span >= -1);
+	bool prev_off_end = false;
+	for (span = span + 1; span < (int)points_.size() - 1; span++) {
+		Point span_vec = points_[span + 1] - points_[span];
+		double t = ((xy - points_[span]) % span_vec) / span_vec.Len2();
+		if (t < -eps) // off the start of this span
+		{
+			if (span == 0) {
+				perp = points_[span];
+				return PerpType::Start;
+			} else if (prev_off_end) {
+				perp = points_[span];
+				return PerpType::Vertex;
+			}
+		} else if (t > 1 + eps) // off the end of this span
+		{
+			if (span == (int)points_.size() - 2) {
+				perp = points_[span + 1];
+				return PerpType::End;
+			}
+			prev_off_end = true;
+		} else // a true perpendicular
+		{
+			perp = points_[span] + span_vec * t;
+			return PerpType::Perpendicular;
+		}
+	}
+	return PerpType::None;
+}
+
+Pwl Pwl::Compose(Pwl const &other, const double eps) const
+{
+	double this_x = points_[0].x, this_y = points_[0].y;
+	int this_span = 0, other_span = other.findSpan(this_y, 0);
+	Pwl result({ { this_x, other.Eval(this_y, &other_span, false) } });
+	while (this_span != (int)points_.size() - 1) {
+		double dx = points_[this_span + 1].x - points_[this_span].x,
+		       dy = points_[this_span + 1].y - points_[this_span].y;
+		if (abs(dy) > eps &&
+		    other_span + 1 < (int)other.points_.size() &&
+		    points_[this_span + 1].y >=
+			    other.points_[other_span + 1].x + eps) {
+			// next control point in result will be where this
+			// function's y reaches the next span in other
+			this_x = points_[this_span].x +
+				 (other.points_[other_span + 1].x -
+				  points_[this_span].y) * dx / dy;
+			this_y = other.points_[++other_span].x;
+		} else if (abs(dy) > eps && other_span > 0 &&
+			   points_[this_span + 1].y <=
+				   other.points_[other_span - 1].x - eps) {
+			// next control point in result will be where this
+			// function's y reaches the previous span in other
+			this_x = points_[this_span].x +
+				 (other.points_[other_span + 1].x -
+				  points_[this_span].y) * dx / dy;
+			this_y = other.points_[--other_span].x;
+		} else {
+			// we stay in the same span in other
+			this_span++;
+			this_x = points_[this_span].x,
+			this_y = points_[this_span].y;
+		}
+		result.Append(this_x, other.Eval(this_y, &other_span, false),
+			      eps);
+	}
+	return result;
+}
+
+void Pwl::Map(std::function<void(double x, double y)> f) const
+{
+	for (auto &pt : points_)
+		f(pt.x, pt.y);
+}
+
+void Pwl::Map2(Pwl const &pwl0, Pwl const &pwl1,
+	       std::function<void(double x, double y0, double y1)> f)
+{
+	int span0 = 0, span1 = 0;
+	double x = std::min(pwl0.points_[0].x, pwl1.points_[0].x);
+	f(x, pwl0.Eval(x, &span0, false), pwl1.Eval(x, &span1, false));
+	while (span0 < (int)pwl0.points_.size() - 1 ||
+	       span1 < (int)pwl1.points_.size() - 1) {
+		if (span0 == (int)pwl0.points_.size() - 1)
+			x = pwl1.points_[++span1].x;
+		else if (span1 == (int)pwl1.points_.size() - 1)
+			x = pwl0.points_[++span0].x;
+		else if (pwl0.points_[span0 + 1].x > pwl1.points_[span1 + 1].x)
+			x = pwl1.points_[++span1].x;
+		else
+			x = pwl0.points_[++span0].x;
+		f(x, pwl0.Eval(x, &span0, false), pwl1.Eval(x, &span1, false));
+	}
+}
+
+Pwl Pwl::Combine(Pwl const &pwl0, Pwl const &pwl1,
+		 std::function<double(double x, double y0, double y1)> f,
+		 const double eps)
+{
+	Pwl result;
+	Map2(pwl0, pwl1, [&](double x, double y0, double y1) {
+		result.Append(x, f(x, y0, y1), eps);
+	});
+	return result;
+}
+
+void Pwl::MatchDomain(Interval const &domain, bool clip, const double eps)
+{
+	int span = 0;
+	Prepend(domain.start, Eval(clip ? points_[0].x : domain.start, &span),
+		eps);
+	span = points_.size() - 2;
+	Append(domain.end, Eval(clip ? points_.back().x : domain.end, &span),
+	       eps);
+}
+
+Pwl &Pwl::operator*=(double d)
+{
+	for (auto &pt : points_)
+		pt.y *= d;
+	return *this;
+}
+
+void Pwl::Debug(FILE *fp) const
+{
+	fprintf(fp, "Pwl {\n");
+	for (auto &p : points_)
+		fprintf(fp, "\t(%g, %g)\n", p.x, p.y);
+	fprintf(fp, "}\n");
+}