wehub-resource-sync
72 lines
2.0 KiB
C++
72 lines
2.0 KiB
C++
/* ******************************************************************************
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*
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*
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* This program and the accompanying materials are made available under the
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* terms of the Apache License, Version 2.0 which is available at
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* https://www.apache.org/licenses/LICENSE-2.0.
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*
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* See the NOTICE file distributed with this work for additional
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* information regarding copyright ownership.
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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* SPDX-License-Identifier: Apache-2.0
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******************************************************************************/
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//
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// @author raver119@gmail.com
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//
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#include <helpers/helper_hash.h>
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#include <helpers/logger.h>
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namespace sd {
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namespace ops {
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HashHelper& HashHelper::getInstance() {
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static HashHelper instance;
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return instance;
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}
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LongType HashHelper::getLongHash(std::string& str) {
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_locker.lock();
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if (!_isInit) {
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sd_verbose("Building HashUtil table\n", "");
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unsigned long long h = 0x544B2FBACAAF1684L;
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for (int i = 0; i < 256; i++) {
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for (int j = 0; j < 31; j++) {
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h = (((unsigned long long)h) >> 7) ^ h;
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h = (h << 11) ^ h;
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h = (((unsigned long long)h) >> 10) ^ h;
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}
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_byteTable[i] = h;
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}
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_isInit = true;
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}
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_locker.unlock();
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//note: DO NOT change this type.
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//when something like thread sanitizer + cuda is used
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//the offsets can get absurdly big.
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//you get errors like: left shift of 11 places cannot be represented in type
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unsigned long long h = HSTART;
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unsigned long long hmult = HMULT;
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LongType len = str.size();
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for (int i = 0; i < len; i++) {
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char ch = str.at(i);
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auto uch = (unsigned char)ch;
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h = (h * hmult) ^ _byteTable[ch & 0xff];
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h = (h * hmult) ^ _byteTable[(uch >> 8) & 0xff];
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}
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return h;
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}
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} // namespace ops
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} // namespace sd
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