Add XorShift, SplitMix64, WyRandom, PCG, and XoroShiro generators

Co-authored-by: 8e8m <248551607+8e8m@users.noreply.github.com>

1 files changed, 89 insertions, 0 deletions

diff --git a/source/splitmix64.c b/source/splitmix64.c
new file mode 100644
index 0000000..c840258
--- /dev/null
+++ b/source/splitmix64.c
@@ -0,0 +1,89 @@
+/* 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 splitmix64 splitmix64.c -lm @STOP
+ */
+
+#include "splitmix64.h"
+
+void splitmix64_init(splitmix64_t *rng, uint64_t seed) {
+    rng->state = seed;
+}
+
+uint32_t splitmix64_next_uint(splitmix64_t *rng) {
+    rng->state += 0x9E3779B97F4A7C15ULL;
+    
+    uint64_t z = rng->state;
+    z = (z ^ (z >> 30)) * 0xBF58476D1CE4E5B9ULL;
+    z = (z ^ (z >> 27)) * 0x94D049BB133111EBULL;
+    z ^= z >> 31;
+    
+    return (uint32_t)z;
+}
+
+uint64_t splitmix64_next_ulong(splitmix64_t *rng) {
+    rng->state += 0x9E3779B97F4A7C15ULL;
+    
+    uint64_t z = rng->state;
+    z = (z ^ (z >> 30)) * 0xBF58476D1CE4E5B9ULL;
+    z = (z ^ (z >> 27)) * 0x94D049BB133111EBULL;
+    z ^= z >> 31;
+    
+    return z;
+}
+
+float splitmix64_next_float(splitmix64_t *rng) {
+    uint32_t value = splitmix64_next_uint(rng);
+    return (value >> 8) * 0x1.0p-24f;
+}
+
+double splitmix64_next_double(splitmix64_t *rng) {
+    uint64_t value = splitmix64_next_ulong(rng);
+    return (value >> 11) * 0x1.0p-53;
+}
+
+#ifdef SPLITMIX64_TEST_MAIN
+#include <stdio.h>
+#include <time.h>
+
+int main(void) {
+    splitmix64_t rng;
+    
+    printf("SplitMix64 C Implementation Test\n");
+    printf("=================================\n\n");
+    
+    splitmix64_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", splitmix64_next_uint(&rng));
+    }
+    
+    printf("\nFirst 10 uint64_t values:\n");
+    splitmix64_init(&rng, 42);
+    for (int i = 0; i < 10; i++) {
+        printf("  %llu\n", (unsigned long long)splitmix64_next_ulong(&rng));
+    }
+    
+    printf("\nFirst 10 float values:\n");
+    splitmix64_init(&rng, 42);
+    for (int i = 0; i < 10; i++) {
+        printf("  %.6f\n", splitmix64_next_float(&rng));
+    }
+    
+    printf("\nPerformance test: generating 10 million uint64_t values...\n");
+    splitmix64_init(&rng, (uint64_t)time(NULL));
+    clock_t start = clock();
+    uint64_t sum = 0;
+    for (int i = 0; i < 10000000; i++) {
+        sum += splitmix64_next_ulong(&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