67 lines
1.7 KiB
C
67 lines
1.7 KiB
C
/*
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* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The OpenAirInterface Software Alliance licenses this file to You under
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* the OAI Public License, Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.openairinterface.org/?page_id=698
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*
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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,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*-------------------------------------------------------------------------------
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* For more information about the OpenAirInterface (OAI) Software Alliance:
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* contact@openairinterface.org
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*/
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#include <simde/x86/avx512/lzcnt.h>
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unsigned char log2_approx(unsigned int x)
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{
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const unsigned int round_val = 3037000499U; // 2^31.5
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if (!x)
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return 0;
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int l2 = simde_x_clz32(x);
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if (x > (round_val >> l2))
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l2 = 32 - l2;
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else
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l2 = 31 - l2;
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return l2;
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}
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unsigned char factor2(unsigned int x)
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{
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unsigned char l2 = 0;
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int i;
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for (i = 0; i < 31; i++)
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if ((x & (1 << i)) != 0)
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break;
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l2 = i;
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return l2;
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}
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unsigned char log2_approx64(unsigned long long int x)
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{
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const unsigned long long round_val = 13043817825332782212ULL; // 2^63.5
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if (!x)
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return 0;
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int l2 = simde_x_clz64(x);
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if (x > (round_val >> l2))
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l2 = 64 - l2;
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else
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l2 = 63 - l2;
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return l2;
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}
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