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

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

1 files changed, 105 insertions, 0 deletions

diff --git a/source/wy_random.c b/source/wy_random.c
new file mode 100644
index 0000000..dcec829
--- /dev/null
+++ b/source/wy_random.c
@@ -0,0 +1,105 @@
+/* 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 wy_random wy_random.c -lm @STOP
+ */
+
+#include "wy_random.h"
+
+#define WY_PRIME0 0xa0761d6478bd642fULL
+#define WY_PRIME1 0xe7037ed1a0b428dbULL
+
+/* Multiply two 64-bit integers and return hi and lo parts of 128-bit result */
+static inline void multiply_64(uint64_t x, uint64_t y, uint64_t *hi, uint64_t *lo) {
+    uint64_t x0 = (uint32_t)x;
+    uint64_t x1 = x >> 32;
+    uint64_t y0 = (uint32_t)y;
+    uint64_t y1 = y >> 32;
+    
+    uint64_t p11 = x1 * y1;
+    uint64_t p01 = x0 * y1;
+    uint64_t p10 = x1 * y0;
+    uint64_t p00 = x0 * y0;
+    
+    uint64_t middle = p10 + (p00 >> 32) + (uint32_t)p01;
+    
+    *lo = (middle << 32) | (uint32_t)p00;
+    *hi = p11 + (middle >> 32) + (p01 >> 32);
+}
+
+/* MUM (MUltiply and Mix) operation */
+static inline uint64_t mum(uint64_t x, uint64_t y) {
+    uint64_t hi, lo;
+    multiply_64(x, y, &hi, &lo);
+    return hi ^ lo;
+}
+
+void wy_init(wy_random_t *rng, uint64_t seed) {
+    rng->state = seed;
+}
+
+uint32_t wy_next_uint(wy_random_t *rng) {
+    rng->state += WY_PRIME0;
+    return (uint32_t)mum(rng->state ^ WY_PRIME1, rng->state);
+}
+
+uint64_t wy_next_ulong(wy_random_t *rng) {
+    rng->state += WY_PRIME0;
+    return mum(rng->state ^ WY_PRIME1, rng->state);
+}
+
+float wy_next_float(wy_random_t *rng) {
+    uint32_t value = wy_next_uint(rng);
+    return (value >> 8) * 0x1.0p-24f;
+}
+
+double wy_next_double(wy_random_t *rng) {
+    uint64_t value = wy_next_ulong(rng);
+    return (value >> 11) * 0x1.0p-53;
+}
+
+#ifdef WY_TEST_MAIN
+#include <stdio.h>
+#include <time.h>
+
+int main(void) {
+    wy_random_t rng;
+    
+    printf("WyRandom C Implementation Test\n");
+    printf("===============================\n\n");
+    
+    wy_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", wy_next_uint(&rng));
+    }
+    
+    printf("\nFirst 10 uint64_t values:\n");
+    wy_init(&rng, 42);
+    for (int i = 0; i < 10; i++) {
+        printf("  %llu\n", (unsigned long long)wy_next_ulong(&rng));
+    }
+    
+    printf("\nFirst 10 float values:\n");
+    wy_init(&rng, 42);
+    for (int i = 0; i < 10; i++) {
+        printf("  %.6f\n", wy_next_float(&rng));
+    }
+    
+    printf("\nPerformance test: generating 10 million uint64_t values...\n");
+    wy_init(&rng, (uint64_t)time(NULL));
+    clock_t start = clock();
+    uint64_t sum = 0;
+    for (int i = 0; i < 10000000; i++) {
+        sum += wy_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