Move Zlib and Hashing libs to third_party directory

third_party/hashing/hashers/crc32.h

@@ -0,0 +1,47 @@
+// //////////////////////////////////////////////////////////
+// crc32.h
+// Copyright (c) 2014 Stephan Brumme. All rights reserved.
+// see http://create.stephan-brumme.com/disclaimer.html
+//
+
+#pragma once
+
+#include "../hashing.h"
+
+/// compute CRC32 hash, based on Intel's Slicing-by-8 algorithm
+/** Usage:
+    CRC32 crc32;
+    std::string myHash  = crc32("Hello World");     // std::string
+    std::string myHash2 = crc32("How are you", 11); // arbitrary data, 11 bytes
+
+    // or in a streaming fashion:
+
+    CRC32 crc32;
+    while (more data available)
+      crc32.add(pointer to fresh data, number of new bytes);
+    std::string myHash3 = crc32.getHash();
+  */
+class CRC32 //: public Hash
+{
+public:
+  /// same as reset()
+  CRC32();
+
+  /// compute CRC32 of a memory block
+  const char* operator()(const void* data, size_t numBytes);
+  /// compute CRC32 of a string, excluding final zero
+  const char* operator()(const char* text, size_t size);
+
+  /// add arbitrary number of bytes
+  void add(const void* data, size_t numBytes);
+
+  /// return latest hash as 16 hex characters
+  const char* getHash();
+
+  /// restart
+  void reset();
+
+private:
+  /// hash
+  uint32_t m_hash;
+};