/**************************************************************************** * libs/libc/symtab/symtab_findbyname.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: symtab_findbyname * * Description: * Find the symbol in the symbol table with the matching name. * This version assumes that table is not ordered with respect to symbol * name and, hence, access time will be linear with respect to nsyms. * * Returned Value: * A reference to the symbol table entry if an entry with the matching * name is found; NULL is returned if the entry is not found. * ****************************************************************************/ FAR const struct symtab_s * symtab_findbyname(FAR const struct symtab_s *symtab, FAR const char *name, int nsyms) { #ifdef CONFIG_SYMTAB_ORDEREDBYNAME int low = 0; int high = nsyms - 1; int mid; int cmp; #endif if (symtab == NULL) { DEBUGASSERT(nsyms == 0); return NULL; } #ifdef CONFIG_SYMTAB_DECORATED if (name[0] == '_') { name++; } #endif DEBUGASSERT(name != NULL); #ifdef CONFIG_SYMTAB_ORDEREDBYNAME while (low < high) { /* Compare the name to the one in the middle. (or just below * the middle in the case where one is even and one is odd). */ mid = (low + high) >> 1; cmp = strcmp(name, symtab[mid].sym_name); if (cmp < 0) { /* name < symtab[mid].sym_name * * NOTE: Because of truncation in the calculation of 'mid'. * 'mid' could be equal to 'low' */ high = mid > low ? mid - 1 : low; } else if (cmp > 0) { /* name > symtab[mid].sym_name */ low = mid + 1; } else { /* symtab[mid].sym_name == name */ return &symtab[mid]; } } /* low == high... One final check. We might not have actually tested * the final symtab[] name. * * Example: Only the last pass through loop, suppose low = 1, high = 2, * mid = 1, and symtab[high].sym_name == name. Then we would get here * with low = 2, high = 2, but symtab[2].sym_name was never tested. */ return strcmp(name, symtab[low].sym_name) == 0 ? &symtab[low] : NULL; #else for (; nsyms > 0; symtab++, nsyms--) { if (strcmp(name, symtab->sym_name) == 0) { return symtab; } } return NULL; #endif }