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backend/node_modules/mnemonist/utils/murmurhash3.js

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+/* eslint no-fallthrough: 0 */
+/**
+ * Mnemonist MurmurHash 3
+ * =======================
+ *
+ * Straightforward implementation of the third version of MurmurHash.
+ *
+ * Note: this piece of code belong to haschisch.
+ */
+
+/**
+ * Various helpers.
+ */
+function mul32(a, b) {
+  return (a & 0xffff) * b + (((a >>> 16) * b & 0xffff) << 16) & 0xffffffff;
+}
+
+function sum32(a, b) {
+  return (a & 0xffff) + (b >>> 16) + (((a >>> 16) + b & 0xffff) << 16) & 0xffffffff;
+}
+
+function rotl32(a, b) {
+  return (a << b) | (a >>> (32 - b));
+}
+
+/**
+ * MumurHash3 function.
+ *
+ * @param  {number}    seed - Seed.
+ * @param  {ByteArray} data - Data.
+ */
+module.exports = function murmurhash3(seed, data) {
+  var c1 = 0xcc9e2d51,
+      c2 = 0x1b873593,
+      r1 = 15,
+      r2 = 13,
+      m = 5,
+      n = 0x6b64e654;
+
+  var hash = seed,
+      k1,
+      i,
+      l;
+
+  for (i = 0, l = data.length - 4; i <= l; i += 4) {
+    k1 = (
+      data[i] |
+      (data[i + 1] << 8) |
+      (data[i + 2] << 16) |
+      (data[i + 3] << 24)
+    );
+
+    k1 = mul32(k1, c1);
+    k1 = rotl32(k1, r1);
+    k1 = mul32(k1, c2);
+
+    hash ^= k1;
+    hash = rotl32(hash, r2);
+    hash = mul32(hash, m);
+    hash = sum32(hash, n);
+  }
+
+  k1 = 0;
+
+  switch (data.length & 3) {
+    case 3:
+      k1 ^= data[i + 2] << 16;
+    case 2:
+      k1 ^= data[i + 1] << 8;
+    case 1:
+      k1 ^= data[i];
+      k1 = mul32(k1, c1);
+      k1 = rotl32(k1, r1);
+      k1 = mul32(k1, c2);
+      hash ^= k1;
+    default:
+  }
+
+  hash ^= data.length;
+  hash ^= hash >>> 16;
+  hash = mul32(hash, 0x85ebca6b);
+  hash ^= hash >>> 13;
+  hash = mul32(hash, 0xc2b2ae35);
+  hash ^= hash >>> 16;
+
+  return hash >>> 0;
+};