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/****************************************************************************
* binfmt/symtab_findorderedbyname.c
*
* Copyright (C) 2009, 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <string.h>
#include <debug.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/binfmt/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 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
*
* 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;
}
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