cosmopolitan/libc/str/strncmp.c

36 lines
2.3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/str/str.h"
/**
* Compares NUL-terminated strings w/ limit.
*
* @param a is first non-null NUL-terminated string pointer
* @param b is second non-null NUL-terminated string pointer
* @return is <0, 0, or >0 based on uint8_t comparison
* @asyncsignalsafe
*/
int strncmp(const char *a, const char *b, size_t n) {
size_t i = 0;
if (!n-- || a == b) return 0;
while (a[i] == b[i] && b[i] && i < n) ++i;
return (a[i] & 0xff) - (b[i] & 0xff);
}