132 lines
3.8 KiB
C
132 lines
3.8 KiB
C
/****************************************************************************
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* libs/libc/symtab/symtab_findbyname.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/config.h>
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#include <string.h>
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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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#include <nuttx/symtab.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: symtab_findbyname
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*
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* Description:
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* Find the symbol in the symbol table with the matching name.
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* This version assumes that table is not ordered with respect to symbol
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* name and, hence, access time will be linear with respect to nsyms.
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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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* name is found; NULL is returned if the entry is not found.
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*
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****************************************************************************/
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FAR const struct symtab_s *
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symtab_findbyname(FAR const struct symtab_s *symtab,
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FAR const char *name, int nsyms)
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{
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#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
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int low = 0;
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int high = nsyms - 1;
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int mid;
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int cmp;
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#endif
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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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#ifdef CONFIG_SYMTAB_DECORATED
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if (name[0] == '_')
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{
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name++;
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}
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#endif
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DEBUGASSERT(name != NULL);
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#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
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while (low < high)
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{
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/* Compare the name to the one in the middle. (or just below
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* the middle in the case where one is even and one is odd).
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*/
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mid = (low + high) >> 1;
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cmp = strcmp(name, symtab[mid].sym_name);
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if (cmp < 0)
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{
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/* name < symtab[mid].sym_name
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*
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* NOTE: Because of truncation in the calculation of 'mid'.
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* 'mid' could be equal to 'low'
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*/
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high = mid > low ? mid - 1 : low;
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}
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else if (cmp > 0)
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{
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/* name > symtab[mid].sym_name */
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low = mid + 1;
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}
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else
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{
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/* symtab[mid].sym_name == name */
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return &symtab[mid];
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}
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}
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/* low == high... One final check. We might not have actually tested
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* the final symtab[] name.
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*
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* Example: Only the last pass through loop, suppose low = 1, high = 2,
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* mid = 1, and symtab[high].sym_name == name. Then we would get here
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* with low = 2, high = 2, but symtab[2].sym_name was never tested.
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*/
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return strcmp(name, symtab[low].sym_name) == 0 ? &symtab[low] : NULL;
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#else
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for (; nsyms > 0; symtab++, nsyms--)
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{
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if (strcmp(name, symtab->sym_name) == 0)
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{
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return symtab;
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}
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}
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return NULL;
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#endif
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}
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