cardinality.cuh

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#pragma once
 
#include <cuda/std/cmath>
#include <cuda/std/cstdint>
#include <cuda/std/limits>
 
namespace cuddl::detail {
 
constexpr double hash_range = 0x1p64;
 
__host__ __device__ inline double
minimum_mle(double bucket_count, double empty_count, double sum_restored) noexcept {
    auto const filled = bucket_count - empty_count;
    if (filled <= 0.0) {
        return 0.0;
    }
    return bucket_count * filled / (empty_count + sum_restored / hash_range);
}
 
__host__ __device__ inline double
mean_m(double bucket_count, double filled, double sum_restored) noexcept {
    if (filled <= 0.0 || sum_restored <= 0.0) {
        return 0.0;
    }
    return bucket_count * filled * hash_range / sum_restored;
}
 
__host__ __device__ inline double
cardinality(double bucket_count, double empty_count, double sum_restored) noexcept {
    return minimum_mle(bucket_count, empty_count, sum_restored);
}
 
__host__ __device__ inline float
minimum_mle_f32(float bucket_count, float empty_count, float sum_restored) noexcept {
    auto const filled = bucket_count - empty_count;
    if (filled <= 0.0f) {
        return 0.0f;
    }
    return bucket_count * filled /
           (empty_count + sum_restored / static_cast<float>(hash_range));
}
 
__host__ __device__ inline float
mean_m_f32(float bucket_count, float filled, float sum_restored) noexcept {
    if (filled <= 0.0f || sum_restored <= 0.0f) {
        return 0.0f;
    }
    return bucket_count * filled * static_cast<float>(hash_range) / sum_restored;
}
 
__host__ __device__ inline float
cardinality_f32(float bucket_count, float empty_count, float sum_restored) noexcept {
    return minimum_mle_f32(bucket_count, empty_count, sum_restored);
}
 
}  // namespace cuddl::detail