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// ----------------------------------------------------------------------------
// Copyright (c) 2018-2023 www.open3d.org
// SPDX-License-Identifier: MIT
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// ----------------------------------------------------------------------------
// original path: faiss/faiss/gpu/utils/Limits.cuh
// ----------------------------------------------------------------------------

#pragma once

#include <limits>

#include "open3d/core/nns/kernel/Pair.cuh"

namespace open3d {
namespace core {

template <typename T>
struct Limits {};

// Unfortunately we can't use constexpr because there is no
// constexpr constructor for half
// FIXME: faiss CPU uses +/-FLT_MAX instead of +/-infinity
constexpr float kFloatMax = std::numeric_limits<float>::max();
constexpr float kFloatMin = std::numeric_limits<float>::lowest();

template <>
struct Limits<float> {
    static __device__ __host__ inline float getMin() { return kFloatMin; }
    static __device__ __host__ inline float getMax() { return kFloatMax; }
};

constexpr double kDoubleMax = std::numeric_limits<double>::max();
constexpr double kDoubleMin = std::numeric_limits<double>::lowest();

template <>
struct Limits<double> {
    static __device__ __host__ inline double getMin() { return kDoubleMin; }
    static __device__ __host__ inline double getMax() { return kDoubleMax; }
};

constexpr int kIntMax = std::numeric_limits<int>::max();
constexpr int kIntMin = std::numeric_limits<int>::lowest();

template <>
struct Limits<int> {
    static __device__ __host__ inline int getMin() { return kIntMin; }
    static __device__ __host__ inline int getMax() { return kIntMax; }
};

template <typename K, typename V>
struct Limits<Pair<K, V>> {
    static __device__ __host__ inline Pair<K, V> getMin() {
        return Pair<K, V>(Limits<K>::getMin(), Limits<V>::getMin());
    }

    static __device__ __host__ inline Pair<K, V> getMax() {
        return Pair<K, V>(Limits<K>::getMax(), Limits<V>::getMax());
    }
};

}  // namespace core
}  // namespace open3d