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Diffstat (limited to 'nuttx/binfmt/symtab_findorderedbyname.c')
-rw-r--r-- | nuttx/binfmt/symtab_findorderedbyname.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/nuttx/binfmt/symtab_findorderedbyname.c b/nuttx/binfmt/symtab_findorderedbyname.c new file mode 100644 index 000000000..9c7f6d5cf --- /dev/null +++ b/nuttx/binfmt/symtab_findorderedbyname.c @@ -0,0 +1,140 @@ +/**************************************************************************** + * binfmt/symtab_findorderedbyname.c + * + * Copyright (C) 2009 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> +#include <sys/types.h> + +#include <string.h> +#include <debug.h> +#include <assert.h> +#include <errno.h> + +#include <nuttx/symtab.h> + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/*********************************************************************** + * Public Functions + ***********************************************************************/ + +/**************************************************************************** + * Name: symtab_findorderedbyname + * + * Description: + * Find the symbol in the symbol table with the matching name. + * This version assumes that table ordered with respect to symbol name. + * + * This function uses qsort() to implement the search and, hence, is a lot + * larger than symbtab_findbyname(). This function not be used, unless + * the symbol table is large and the performance benefit is worth the + * increased size. + * + * 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_findorderedbyname(FAR const struct symtab_s *symtab, + FAR const char *name, int nsyms) +{ + int low = 0; + int high = nsyms -1; + int mid; + int cmp; + + /* Loop until the range has been isolated to a single symbol table + * entry that may or may not match the search name. + */ + + DEBUGASSERT(symtab != NULL && name != NULL); + 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 */ + + high = mid - 1; + } + 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; +} + |