/* SPDX-License-Identifier: BSD-2-Clause */ /* * Copyright (C) 2019, Raspberry Pi Ltd * * pwl.cpp - piecewise linear functions */ #include #include #include "pwl.h" using namespace RPiController; int Pwl::read(const libcamera::YamlObject ¶ms) { if (!params.size() || params.size() % 2) return -EINVAL; const auto &list = params.asList(); for (auto it = list.begin(); it != list.end(); it++) { auto x = it->get(); if (!x) return -EINVAL; if (it != list.begin() && *x <= points_.back().x) return -EINVAL; auto y = (++it)->get(); if (!y) return -EINVAL; points_.push_back(Point(*x, *y)); } return 0; } 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 *spanPtr, bool updateSpan) const { int span = findSpan(x, spanPtr && *spanPtr != -1 ? *spanPtr : points_.size() / 2 - 1); if (spanPtr && updateSpan) *spanPtr = 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 lastSpan = points_.size() - 2; /* * some algorithms may call us with span pointing directly at the last * control point */ span = std::max(0, std::min(lastSpan, span)); while (span < lastSpan && 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 prevOffEnd = false; for (span = span + 1; span < (int)points_.size() - 1; span++) { Point spanVec = points_[span + 1] - points_[span]; double t = ((xy - points_[span]) % spanVec) / spanVec.len2(); if (t < -eps) /* off the start of this span */ { if (span == 0) { perp = points_[span]; return PerpType::Start; } else if (prevOffEnd) { 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; } prevOffEnd = true; } else /* a true perpendicular */ { perp = points_[span] + spanVec * t; return PerpType::Perpendicular; } } return PerpType::None; } Pwl Pwl::inverse(bool *trueInverse, const double eps) const { bool appended = false, prepended = false, neither = false; Pwl inverse; for (Point const &p : points_) { if (inverse.empty()) inverse.append(p.y, p.x, eps); else if (std::abs(inverse.points_.back().x - p.y) <= eps || std::abs(inverse.points_.front().x - p.y) <= eps) /* do nothing */; else if (p.y > inverse.points_.back().x) { inverse.append(p.y, p.x, eps); appended = true; } else if (p.y < inverse.points_.front().x) { inverse.prepend(p.y, p.x, eps); prepended = true; } else neither = true; } /* * This is not a proper inverse if we found ourselves putting points * onto both ends of the inverse, or if there were points that couldn't * go on either. */ if (trueInverse) *trueInverse = !(neither || (appended && prepended)); return inverse; } Pwl Pwl::compose(Pwl const &other, const double eps) const { double thisX = points_[0].x, thisY = points_[0].y; int thisSpan = 0, otherSpan = other.findSpan(thisY, 0); Pwl result({ { thisX, other.eval(thisY, &otherSpan, false) } }); while (thisSpan != (int)points_.size() - 1) { double dx = points_[thisSpan + 1].x - points_[thisSpan].x, dy = points_[thisSpan + 1].y - points_[thisSpan].y; if (abs(dy) > eps && otherSpan + 1 < (int)other.points_.size() && points_[thisSpan + 1].y >= other.points_[otherSpan + 1].x + eps) { /* * next control point in result will be where this * function's y reaches the next span in other */ thisX = points_[thisSpan].x + (other.points_[otherSpan + 1].x - points_[thisSpan].y) * dx / dy; thisY = other.points_[++otherSpan].x; } else if (abs(dy) > eps && otherSpan > 0 && points_[thisSpan + 1].y <= other.points_[otherSpan - 1].x - eps) { /* * next control point in result will be where this * function's y reaches the previous span in other */ thisX = points_[thisSpan].x + (other.points_[otherSpan + 1].x - points_[thisSpan].y) * dx / dy; thisY = other.points_[--otherSpan].x; } else { /* we stay in the same span in other */ thisSpan++; thisX = points_[thisSpan].x, thisY = points_[thisSpan].y; } result.append(thisX, other.eval(thisY, &otherSpan, false), eps); } return result; } void Pwl::map(std::function f) const { for (auto &pt : points_) f(pt.x, pt.y); } void Pwl::map2(Pwl const &pwl0, Pwl const &pwl1, std::function 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 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"); } id='n122' href='#n122'>122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220