e03599d9ae
Move log2ceil from riscv_pmp to libc. Also, implement log2floor for completeness. These are the run-time alternative to the compile-time macros.
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/****************************************************************************
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* libs/libc/misc/lib_log2floor.c
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*
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* Licensed to the Apache Software Foundation (ASF) 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. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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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, 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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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/lib/math32.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: log2floor
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*
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* Description:
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* Calculate the down-rounded (truncated) power-of-two for input.
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*
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* Input Parameters:
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* x - Argument to calculate the power-of-two from.
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*
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* Returned Value:
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* Power-of-two for argument, rounded (truncated) down.
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*
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****************************************************************************/
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uintptr_t log2floor(uintptr_t x)
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{
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uintptr_t pot = 0;
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for (; x > 1; x >>= 1)
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{
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pot++;
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}
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return pot;
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}
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