Xorshift32

iris_c/main.c

@@ -0,0 +1,9 @@
+#include "random.h"
+#include <stdio.h>
+
+int main() {
+    set_random_seed(1842);
+    uint32_t num = random_u32();
+    printf("%u\n", num);
+    return 0;
+}

iris_c/random.c

@@ -0,0 +1,24 @@
+#include "random.h"
+
+static uint32_t state = 1;
+
+void set_random_seed(uint32_t seed) {
+    state = seed ? seed : 1;
+}
+
+uint32_t random_u32(void) {
+    state ^= state << 13;
+    state ^= state >> 17;
+    state ^= state << 5;
+    return state;
+}
+
+uint32_t random_range(uint32_t max) {
+    if (max == 0) return 0;
+    uint32_t threshold = (0xFFFFFFFFU / max) * max;
+    uint32_t r;
+    do {
+        r = random_u32();
+    } while (r >= threshold);
+    return r % max;
+}

iris_c/random.h

@@ -0,0 +1,10 @@
+#ifndef RANDOM_H
+#define RANDOM_H
+
+#include <stdint.h>
+
+void set_random_seed(uint32_t seed);
+uint32_t random_u32(void);
+uint32_t random_range(uint32_t max);
+
+#endif