nuttx/libs/libc/string/lib_strcmp.c
Oki Minabe 185b1cb1b7 libc/string: strcmp/strncmp cast unsigned char
Summary:
- Cast to unsigned char for strcmp and strncmp
- strcmp and strncmp are described following by opengroup.org

  The sign of a non-zero return value shall be determined by the sign
  of the difference between the values of the first pair of bytes
  (both interpreted as type unsigned char) that differ in the strings
  being compared.

  https://pubs.opengroup.org/onlinepubs/9699919799/functions/strcmp.html
  https://pubs.opengroup.org/onlinepubs/9699919799/functions/strncmp.html

Impact:
- strcmp and strncmp return value

Testing:
- ostest on sabre-6quad:smp w/ qemu

Signed-off-by: Oki Minabe <minabe.oki@gmail.com>
2022-04-23 16:11:00 +03:00

50 lines
1.7 KiB
C

/****************************************************************************
* libs/libc/string/lib_strcmp.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>
/****************************************************************************
* Public Functions
****************************************************************************/
#ifndef CONFIG_LIBC_ARCH_STRCMP
#undef strcmp /* See mm/README.txt */
int strcmp(FAR const char *cs, FAR const char *ct)
{
register int result;
for (; ; )
{
if ((result = (unsigned char)*cs - (unsigned char)*ct++) != 0 ||
!*cs++)
{
break;
}
}
return result;
}
#endif