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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /dviware/dvisvgm/src/XXHashFunction.hpp
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+/*************************************************************************
+** XXHashFunction.hpp **
+** **
+** This file is part of dvisvgm -- a fast DVI to SVG converter **
+** Copyright (C) 2005-2019 Martin Gieseking <martin.gieseking@uos.de> **
+** **
+** This program is free software; you can redistribute it and/or **
+** modify it under the terms of the GNU General Public License as **
+** published by the Free Software Foundation; either version 3 of **
+** the License, or (at your option) any later version. **
+** **
+** This program is distributed in the hope that it will be useful, but **
+** WITHOUT ANY WARRANTY; without even the implied warranty of **
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the **
+** GNU General Public License for more details. **
+** **
+** You should have received a copy of the GNU General Public License **
+** along with this program; if not, see <http://www.gnu.org/licenses/>. **
+*************************************************************************/
+
+#ifndef XXHASHFUNCTION_HPP
+#define XXHASHFUNCTION_HPP
+
+#include <xxhash.h>
+#include "HashFunction.hpp"
+
+
+template <int HASH_SIZE>
+struct XXHInterface {
+};
+
+template<>
+struct XXHInterface<4> {
+ using State = XXH32_state_t;
+ static constexpr auto createState = &XXH32_createState;
+ static constexpr auto freeState = &XXH32_freeState;
+ static constexpr auto reset = &XXH32_reset;
+ static constexpr auto update = &XXH32_update;
+ static constexpr auto digest = &XXH32_digest;
+};
+
+template<>
+struct XXHInterface<8> {
+ using State = XXH64_state_t;
+ static constexpr auto createState = &XXH64_createState;
+ static constexpr auto freeState = &XXH64_freeState;
+ static constexpr auto reset = &XXH64_reset;
+ static constexpr auto update = &XXH64_update;
+ static constexpr auto digest = &XXH64_digest;
+};
+
+
+/** Implements the HashFunction class for the xxHash algorithms. */
+template <int HASH_BYTES>
+class XXHashFunction : public HashFunction {
+ using Interface = XXHInterface<HASH_BYTES>;
+ public:
+ XXHashFunction () : _state(Interface::createState()) {Interface::reset(_state, 0);}
+ XXHashFunction(const char *data, size_t length) : XXHashFunction() {update(data, length);}
+ explicit XXHashFunction(const std::string &data) : XXHashFunction() {update(data);}
+ explicit XXHashFunction(const std::vector<uint8_t> &data) : XXHashFunction() {update(data);}
+ ~XXHashFunction () override {Interface::freeState(_state);}
+ int digestSize () const override {return HASH_BYTES;}
+ void reset () override {Interface::reset(_state, 0);}
+ void update (const char *data, size_t length) override {Interface::update(_state, data, length);}
+ void update (const std::string &data) override {update(data.data(), data.length());}
+ void update (const std::vector<uint8_t> &data) override {update(reinterpret_cast<const char*>(data.data()), data.size());}
+
+ std::vector<uint8_t> digestValue () const override {
+ std::vector<uint8_t> hash(HASH_BYTES);
+ auto digest = Interface::digest(_state);
+ for (int i=HASH_BYTES-1; i >= 0; i--) {
+ hash[i] = digest & 0xff;
+ digest >>= 8;
+ }
+ return hash;
+ }
+
+ static unsigned version () {return XXH_versionNumber();}
+
+ private:
+ typename Interface::State *_state;
+};
+
+using XXH32HashFunction = XXHashFunction<4>;
+using XXH64HashFunction = XXHashFunction<8>;
+
+#endif