Udp

common/network/webudp/WuRng.cpp

@@ -0,0 +1,51 @@
+#include <stdlib.h>
+#include "WuRng.h"
+
+static const char kCharacterTable[] =
+    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+static inline uint64_t rotl(const uint64_t x, int k) {
+  return (x << k) | (x >> (64 - k));
+}
+
+static uint64_t WuGetRngSeed() {
+  uint64_t x = rand();
+  uint64_t z = (x += UINT64_C(0x9E3779B97F4A7C15));
+  z = (z ^ (z >> 30)) * UINT64_C(0xBF58476D1CE4E5B9);
+  z = (z ^ (z >> 27)) * UINT64_C(0x94D049BB133111EB);
+  return z ^ (z >> 31);
+}
+
+static void WuRngInit(WuRngState* state, uint64_t seed) {
+  state->s[0] = seed;
+  state->s[1] = seed;
+}
+
+static uint64_t WuRngNext(WuRngState* state) {
+  const uint64_t s0 = state->s[0];
+  uint64_t s1 = state->s[1];
+  const uint64_t result = s0 + s1;
+
+  s1 ^= s0;
+  state->s[0] = rotl(s0, 55) ^ s1 ^ (s1 << 14);
+  state->s[1] = rotl(s1, 36);
+
+  return result;
+}
+
+void WuRandomString(char* out, size_t length) {
+  WuRngState state;
+  WuRngInit(&state, WuGetRngSeed());
+
+  for (size_t i = 0; i < length; i++) {
+    out[i] = kCharacterTable[WuRngNext(&state) % (sizeof(kCharacterTable) - 1)];
+  }
+}
+
+uint64_t WuRandomU64() {
+  WuRngState state;
+  WuRngInit(&state, WuGetRngSeed());
+  return WuRngNext(&state);
+}
+
+uint32_t WuRandomU32() { return (uint32_t)WuRandomU64(); }