114 lines
3.0 KiB
C++
114 lines
3.0 KiB
C++
/*
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* Created by Brett on 04/01/23.
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* Licensed under GNU General Public License V3.0
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* See LICENSE file for license detail
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*/
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#ifndef BLT_RANDOM_H
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#define BLT_RANDOM_H
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#include <blt/std/types.h>
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#include <random>
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namespace blt::random
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{
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// https://github.com/avaneev/komihash/tree/main
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static inline blt::u32 pcg_hash32(blt::u32 input)
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{
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blt::u32 state = input * 747796405u + 2891336453u;
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blt::u32 word = ((state >> ((state >> 28u) + 4u)) ^ state) * 277803737u;
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return (word >> 22u) ^ word;
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}
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//https://lemire.me/blog/2018/08/15/fast-strongly-universal-64-bit-hashing-everywhere/
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static inline blt::u64 murmur64(blt::u64 h)
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{
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h ^= h >> 33;
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h *= 0xff51afd7ed558ccdL;
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h ^= h >> 33;
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h *= 0xc4ceb9fe1a85ec53L;
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h ^= h >> 33;
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return h;
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}
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static inline double pcg_double32(blt::u32& seed)
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{
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seed = pcg_hash32(seed);
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return static_cast<double>(seed) / static_cast<double>(std::numeric_limits<blt::u32>::max());
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}
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static inline float pcg_float32(blt::u32& seed)
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{
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return static_cast<float>(pcg_double32(seed));
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}
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/**
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* @return random float without changing seed
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*/
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static inline float pcg_float32c(blt::u32 seed)
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{
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return pcg_float32(seed);
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}
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static inline double pcg_double32c(blt::u32 seed)
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{
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return pcg_double32(seed);
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}
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/**
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* @param seed seed for random
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* @param min inclusive min
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* @param max exclusive max
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* @return random int between min (inclusive) and max (exclusive)
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*/
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template<typename T = blt::i32>
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static inline T pcg_random32(blt::u32& seed, T min = 0, T max = 2)
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{
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return static_cast<T>((pcg_double32(seed) * static_cast<double>(max - min)) + static_cast<double>(min));
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}
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template<typename T = blt::i32>
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static inline T pcg_random32c(blt::u32 seed, T min = 0, T max = 2)
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{
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return pcg_random32(seed, min, max);
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}
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static inline double murmur_double64(blt::u64& seed)
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{
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seed = murmur64(seed);
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return static_cast<double>(seed) / static_cast<double>(std::numeric_limits<blt::u64>::max());
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}
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static inline float murmur_float64(blt::u64& seed)
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{
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return static_cast<float>(murmur_double64(seed));
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}
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static inline float murmur_float64c(blt::u64 seed)
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{
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return murmur_float64(seed);
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}
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static inline double murmur_double64c(blt::u64 seed)
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{
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return murmur_double64(seed);
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}
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template<typename T = blt::i32>
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static inline T murmur_random64(blt::u64& seed, T min = 0, T max = 2)
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{
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return static_cast<T>((murmur_double64(seed) * static_cast<double>(max - min)) + static_cast<double>(min));
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}
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template<typename T = blt::i32>
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static inline T murmur_random64c(blt::u64 seed, T min = 0, T max = 2)
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{
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return murmur_random64(seed, min, max);
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}
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}
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#endif //BLT_RANDOM_H
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