1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
/* MIT License - Copyright (c) 2025 wallstop
* Original C# implementation from: https://github.com/wallstop/unity-helpers
* Converted to C for librandom project
*
* @BAKE cc -O2 -Wall -Wextra -std=c99 -o pcg_random pcg_random.c -lm @STOP
*/
#include "pcg_random.h"
static inline uint64_t normalize_increment(uint64_t increment) {
return (increment & 1ULL) == 0 ? increment | 1ULL : increment;
}
void pcg_init(pcg_random_t *rng, uint64_t seed) {
rng->increment = normalize_increment(6554638469ULL);
rng->state = seed;
/* Warm up the state */
pcg_next_uint(rng);
rng->increment = normalize_increment((uint64_t)pcg_next_uint(rng) | ((uint64_t)pcg_next_uint(rng) << 32));
}
void pcg_init_full(pcg_random_t *rng, uint64_t state, uint64_t increment) {
rng->state = state;
rng->increment = normalize_increment(increment);
}
uint32_t pcg_next_uint(pcg_random_t *rng) {
uint64_t old_state = rng->state;
rng->state = old_state * 6364136223846793005ULL + rng->increment;
uint32_t xor_shifted = (uint32_t)(((old_state >> 18) ^ old_state) >> 27);
int rot = (int)(old_state >> 59);
return (xor_shifted >> rot) | (xor_shifted << ((-rot) & 31));
}
uint64_t pcg_next_ulong(pcg_random_t *rng) {
uint64_t high = (uint64_t)pcg_next_uint(rng) << 32;
uint64_t low = (uint64_t)pcg_next_uint(rng);
return high | low;
}
float pcg_next_float(pcg_random_t *rng) {
uint32_t value = pcg_next_uint(rng);
return (value >> 8) * 0x1.0p-24f;
}
double pcg_next_double(pcg_random_t *rng) {
uint64_t value = pcg_next_ulong(rng);
return (value >> 11) * 0x1.0p-53;
}
#ifdef PCG_TEST_MAIN
#include <stdio.h>
#include <time.h>
int main(void) {
pcg_random_t rng;
printf("PCG Random C Implementation Test\n");
printf("=================================\n\n");
pcg_init(&rng, 42);
printf("Testing with seed 42:\n");
printf("First 10 uint32_t values:\n");
for (int i = 0; i < 10; i++) {
printf(" %u\n", pcg_next_uint(&rng));
}
printf("\nFirst 10 uint64_t values:\n");
pcg_init(&rng, 42);
for (int i = 0; i < 10; i++) {
printf(" %llu\n", (unsigned long long)pcg_next_ulong(&rng));
}
printf("\nFirst 10 float values:\n");
pcg_init(&rng, 42);
for (int i = 0; i < 10; i++) {
printf(" %.6f\n", pcg_next_float(&rng));
}
printf("\nPerformance test: generating 10 million uint32_t values...\n");
pcg_init(&rng, (uint64_t)time(NULL));
clock_t start = clock();
uint64_t sum = 0;
for (int i = 0; i < 10000000; i++) {
sum += pcg_next_uint(&rng);
}
clock_t end = clock();
double elapsed = (double)(end - start) / CLOCKS_PER_SEC;
printf("Time: %.3f seconds (sum: %llu to prevent optimization)\n", elapsed, (unsigned long long)sum);
return 0;
}
#endif
|
