nuttx/libs/libc/symtab/symtab_findorderedbyname.c
Alin Jerpelea d6b50a1d3f libs: nxstyle fixes
nxstyle fixes to pass the CI checks

Signed-off-by: Alin Jerpelea <alin.jerpelea@sony.com>
2021-03-03 18:52:53 -08:00

111 lines
3.7 KiB
C

/****************************************************************************
* libs/libc/symtab/symtab_findorderedbyname.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 <nuttx/config.h>
#include <string.h>
#include <debug.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/symtab.h>
/****************************************************************************
* 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;
}