[PATCH v4 2/4] ipa: libipa: Copy pwl from rpi
Kieran Bingham
kieran.bingham at ideasonboard.com
Mon Jun 3 13:11:50 CEST 2024
Quoting Paul Elder (2024-05-31 15:42:59)
> Copy the piecewise linear function code from Raspberry Pi.
>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com>
> Acked-by: David Plowman <david.plowman at raspberrypi.com>
>
> ---
> Changes in v4:
> - update the copy
Files are identical in my check so:
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
> No change in v3
>
> No change in v2
> ---
> src/ipa/libipa/meson.build | 2 +
> src/ipa/libipa/pwl.cpp | 269 +++++++++++++++++++++++++++++++++++++
> src/ipa/libipa/pwl.h | 127 +++++++++++++++++
> 3 files changed, 398 insertions(+)
> create mode 100644 src/ipa/libipa/pwl.cpp
> create mode 100644 src/ipa/libipa/pwl.h
>
> diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build
> index 7ce885da7..8ec9c7847 100644
> --- a/src/ipa/libipa/meson.build
> +++ b/src/ipa/libipa/meson.build
> @@ -8,6 +8,7 @@ libipa_headers = files([
> 'fc_queue.h',
> 'histogram.h',
> 'module.h',
> + 'pwl.h',
> ])
>
> libipa_sources = files([
> @@ -18,6 +19,7 @@ libipa_sources = files([
> 'fc_queue.cpp',
> 'histogram.cpp',
> 'module.cpp',
> + 'pwl.cpp',
> ])
>
> libipa_includes = include_directories('..')
> diff --git a/src/ipa/libipa/pwl.cpp b/src/ipa/libipa/pwl.cpp
> new file mode 100644
> index 000000000..e39123767
> --- /dev/null
> +++ b/src/ipa/libipa/pwl.cpp
> @@ -0,0 +1,269 @@
> +/* SPDX-License-Identifier: BSD-2-Clause */
> +/*
> + * Copyright (C) 2019, Raspberry Pi Ltd
> + *
> + * piecewise linear functions
> + */
> +
> +#include <cassert>
> +#include <cmath>
> +#include <stdexcept>
> +
> +#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<double>();
> + if (!x)
> + return -EINVAL;
> + if (it != list.begin() && *x <= points_.back().x)
> + return -EINVAL;
> +
> + auto y = (++it)->get<double>();
> + 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 (std::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 (std::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<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");
> +}
> diff --git a/src/ipa/libipa/pwl.h b/src/ipa/libipa/pwl.h
> new file mode 100644
> index 000000000..7d5e7e4d3
> --- /dev/null
> +++ b/src/ipa/libipa/pwl.h
> @@ -0,0 +1,127 @@
> +/* SPDX-License-Identifier: BSD-2-Clause */
> +/*
> + * Copyright (C) 2019, Raspberry Pi Ltd
> + *
> + * piecewise linear functions interface
> + */
> +#pragma once
> +
> +#include <functional>
> +#include <math.h>
> +#include <vector>
> +
> +#include "libcamera/internal/yaml_parser.h"
> +
> +namespace RPiController {
> +
> +class Pwl
> +{
> +public:
> + struct Interval {
> + Interval(double _start, double _end)
> + : start(_start), end(_end)
> + {
> + }
> + double start, end;
> + bool contains(double value)
> + {
> + return value >= start && value <= end;
> + }
> + double clip(double value)
> + {
> + return value < start ? start
> + : (value > end ? end : value);
> + }
> + double len() const { return end - start; }
> + };
> + struct Point {
> + Point() : x(0), y(0) {}
> + Point(double _x, double _y)
> + : x(_x), y(_y) {}
> + double x, y;
> + Point operator-(Point const &p) const
> + {
> + return Point(x - p.x, y - p.y);
> + }
> + Point operator+(Point const &p) const
> + {
> + return Point(x + p.x, y + p.y);
> + }
> + double operator%(Point const &p) const
> + {
> + return x * p.x + y * p.y;
> + }
> + Point operator*(double f) const { return Point(x * f, y * f); }
> + Point operator/(double f) const { return Point(x / f, y / f); }
> + double len2() const { return x * x + y * y; }
> + double len() const { return sqrt(len2()); }
> + };
> + Pwl() {}
> + Pwl(std::vector<Point> const &points) : points_(points) {}
> + int read(const libcamera::YamlObject ¶ms);
> + void append(double x, double y, const double eps = 1e-6);
> + void prepend(double x, double y, const double eps = 1e-6);
> + Interval domain() const;
> + Interval range() const;
> + bool empty() const;
> + /*
> + * Evaluate Pwl, optionally supplying an initial guess for the
> + * "span". The "span" may be optionally be updated. If you want to know
> + * the "span" value but don't have an initial guess you can set it to
> + * -1.
> + */
> + double eval(double x, int *spanPtr = nullptr,
> + bool updateSpan = true) const;
> + /*
> + * Find perpendicular closest to xy, starting from span+1 so you can
> + * call it repeatedly to check for multiple closest points (set span to
> + * -1 on the first call). Also returns "pseudo" perpendiculars; see
> + * PerpType enum.
> + */
> + enum class PerpType {
> + None, /* no perpendicular found */
> + Start, /* start of Pwl is closest point */
> + End, /* end of Pwl is closest point */
> + Vertex, /* vertex of Pwl is closest point */
> + Perpendicular /* true perpendicular found */
> + };
> + PerpType invert(Point const &xy, Point &perp, int &span,
> + const double eps = 1e-6) const;
> + /*
> + * Compute the inverse function. Indicate if it is a proper (true)
> + * inverse, or only a best effort (e.g. input was non-monotonic).
> + */
> + Pwl inverse(bool *trueInverse = nullptr, const double eps = 1e-6) const;
> + /* Compose two Pwls together, doing "this" first and "other" after. */
> + Pwl compose(Pwl const &other, const double eps = 1e-6) const;
> + /* Apply function to (x,y) values at every control point. */
> + void map(std::function<void(double x, double y)> f) const;
> + /*
> + * Apply function to (x, y0, y1) values wherever either Pwl has a
> + * control point.
> + */
> + static void map2(Pwl const &pwl0, Pwl const &pwl1,
> + std::function<void(double x, double y0, double y1)> f);
> + /*
> + * Combine two Pwls, meaning we create a new Pwl where the y values are
> + * given by running f wherever either has a knot.
> + */
> + static Pwl
> + combine(Pwl const &pwl0, Pwl const &pwl1,
> + std::function<double(double x, double y0, double y1)> f,
> + const double eps = 1e-6);
> + /*
> + * Make "this" match (at least) the given domain. Any extension my be
> + * clipped or linear.
> + */
> + void matchDomain(Interval const &domain, bool clip = true,
> + const double eps = 1e-6);
> + Pwl &operator*=(double d);
> + void debug(FILE *fp = stdout) const;
> +
> +private:
> + int findSpan(double x, int span) const;
> + std::vector<Point> points_;
> +};
> +
> +} /* namespace RPiController */
> --
> 2.39.2
>
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