99 lines
1.9 KiB
C
99 lines
1.9 KiB
C
#pragma once
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#include <kinc/global.h>
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/*! \file random.h
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\brief Generates values which are kind of random.
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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/// <summary>
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/// Initializes the randomizer with a seed. This is optional but helpful.
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/// </summary>
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/// <param name="seed">A value which should ideally be pretty random</param>
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KINC_FUNC void kinc_random_init(int64_t seed);
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/// <summary>
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/// Returns a random value.
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/// </summary>
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/// <returns>A random value</returns>
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KINC_FUNC int64_t kinc_random_get(void);
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/// <summary>
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/// Returns a value between 0 and max (both inclusive).
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/// </summary>
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/// <returns>A random value</returns>
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KINC_FUNC int64_t kinc_random_get_max(int64_t max);
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/// <summary>
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/// Returns a value between min and max (both inclusive).
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/// </summary>
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/// <returns>A random value</returns>
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KINC_FUNC int64_t kinc_random_get_in(int64_t min, int64_t max);
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#ifdef KINC_IMPLEMENTATION_MATH
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#define KINC_IMPLEMENTATION
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#endif
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#ifdef KINC_IMPLEMENTATION
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#include <limits.h>
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#include <stdlib.h>
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// xoshiro256** 1.0
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static inline uint64_t rotl(const uint64_t x, int k) {
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return (x << k) | (x >> (64 - k));
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}
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static uint64_t s[4] = {1, 2, 3, 4};
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uint64_t next(void) {
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const uint64_t result = rotl(s[1] * 5, 7) * 9;
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const uint64_t t = s[1] << 17;
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s[2] ^= s[0];
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s[3] ^= s[1];
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s[1] ^= s[2];
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s[0] ^= s[3];
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s[2] ^= t;
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s[3] = rotl(s[3], 45);
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return result;
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}
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void kinc_random_init(int64_t seed) {
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s[0] = (uint64_t)seed;
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s[1] = 2;
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s[2] = 3;
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s[3] = 4;
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s[1] = next();
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s[2] = next();
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s[3] = next();
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}
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int64_t kinc_random_get(void) {
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return (int64_t)next();
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}
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int64_t kinc_random_get_max(int64_t max) {
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return kinc_random_get() % (max + 1);
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}
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int64_t kinc_random_get_in(int64_t min, int64_t max) {
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int64_t value = kinc_random_get();
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return (value < -LLONG_MAX ? LLONG_MAX : llabs(value)) % (max + 1 - min) + min;
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}
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#endif
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#ifdef __cplusplus
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}
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#endif
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