2009-06-20 21:17:46 +02:00
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/****************************************************************************
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2018-05-29 21:21:26 +02:00
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* libs/libc/symtab/symtab_findbyvalue.c
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2009-06-20 21:17:46 +02:00
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*
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2021-03-02 15:54:21 +01:00
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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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2009-06-20 21:17:46 +02:00
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*
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2021-03-02 15:54:21 +01:00
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* http://www.apache.org/licenses/LICENSE-2.0
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2009-06-20 21:17:46 +02:00
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*
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2021-03-02 15:54:21 +01:00
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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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2009-06-20 21:17:46 +02:00
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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/config.h>
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2009-12-17 00:23:46 +01:00
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#include <stddef.h>
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2009-06-20 21:17:46 +02:00
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#include <debug.h>
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#include <assert.h>
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#include <errno.h>
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2015-12-13 15:10:01 +01:00
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#include <nuttx/symtab.h>
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2009-06-20 21:17:46 +02:00
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2015-10-03 01:43:18 +02:00
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/****************************************************************************
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2009-06-20 21:17:46 +02:00
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* Public Functions
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2015-10-03 01:43:18 +02:00
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****************************************************************************/
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2009-06-20 21:17:46 +02:00
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/****************************************************************************
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* Name: symtab_findbyvalue
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*
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* Description:
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* Find the symbol in the symbol table whose value closest (but not greater
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2021-03-02 14:33:27 +01:00
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* than), the provided value. This version assumes that table is not
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2021-03-15 10:35:47 +01:00
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* ordered with respect to symbol value and, hence, access time will be
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2021-03-02 14:33:27 +01:00
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* linear with respect to nsyms.
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2009-06-20 21:17:46 +02:00
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*
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* Returned Value:
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* A reference to the symbol table entry if an entry with the matching
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2021-03-15 10:35:47 +01:00
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* value is found; NULL is returned if the entry is not found.
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2009-06-20 21:17:46 +02:00
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*
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****************************************************************************/
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FAR const struct symtab_s *
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symtab_findbyvalue(FAR const struct symtab_s *symtab,
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FAR void *value, int nsyms)
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{
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2021-12-21 17:04:41 +01:00
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#ifndef CONFIG_SYMTAB_ORDEREDBYVALUE
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2009-06-20 21:17:46 +02:00
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FAR const struct symtab_s *retval = NULL;
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2021-12-21 17:04:41 +01:00
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#else
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int high = nsyms - 1;
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int mid = high >> 1;
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int low = 0;
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#endif
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2009-06-20 21:17:46 +02:00
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2022-01-27 05:23:17 +01:00
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if (symtab == NULL)
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{
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DEBUGASSERT(nsyms == 0);
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return NULL;
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}
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2021-12-21 17:04:41 +01:00
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#ifdef CONFIG_SYMTAB_ORDEREDBYVALUE
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while (high >= low)
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{
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mid = (low + high) >> 1;
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if (symtab[mid].sym_value == value)
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{
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break;
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}
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else if (symtab[mid].sym_value > value)
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{
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if (symtab[mid - 1].sym_value <= value)
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{
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mid -= 1;
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break;
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}
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else
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{
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high = mid - 1;
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}
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}
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else if (symtab[mid].sym_value < value)
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{
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if (symtab[mid + 1].sym_value >= value)
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{
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break;
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}
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else
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{
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low = mid + 1;
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}
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}
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}
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return &symtab[mid];
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#else /* CONFIG_SYMTAB_ORDEREDBYVALUE */
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2009-06-20 21:17:46 +02:00
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for (; nsyms > 0; symtab++, nsyms--)
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{
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2021-03-02 14:33:27 +01:00
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/* Look for symbols of lesser or equal value (probably address) to
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* value
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*/
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2009-06-20 21:17:46 +02:00
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if (symtab->sym_value <= value)
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{
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/* Found one. Is it the largest we have found so far? */
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if (!retval || symtab->sym_value > retval->sym_value)
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{
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/* Yes, then it is the new candidate for the symbol whose value
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* just below 'value'
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*/
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retval = symtab;
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2021-03-02 14:33:27 +01:00
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/* If it is exactly equal to the search 'value', then we might
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* as well terminate early because we can't do any better than
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* that.
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2009-06-20 21:17:46 +02:00
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*/
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if (retval->sym_value == value)
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{
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break;
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}
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}
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}
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}
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return retval;
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2021-12-21 17:04:41 +01:00
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#endif /* CONFIG_SYMTAB_ORDEREDBYVALUE */
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2009-06-20 21:17:46 +02:00
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}
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