diff options
Diffstat (limited to 'lib/libc/string/swab.c')
| -rw-r--r-- | lib/libc/string/swab.c | 66 |
1 files changed, 14 insertions, 52 deletions
diff --git a/lib/libc/string/swab.c b/lib/libc/string/swab.c index 1a30ce813784..ed4436a49810 100644 --- a/lib/libc/string/swab.c +++ b/lib/libc/string/swab.c @@ -1,63 +1,25 @@ /*- - * SPDX-License-Identifier: BSD-3-Clause - * - * Copyright (c) 1988, 1993 - * The Regents of the University of California. All rights reserved. - * - * This code is derived from software contributed to Berkeley by - * Jeffrey Mogul. - * - * 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 of the University 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 REGENTS 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 REGENTS 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. + * SPDX-License-Identifier: BSD-2-Clause + * Copyright (c) 2024 rilysh <nightquick@proton.me> */ -#if defined(LIBC_SCCS) && !defined(lint) -static char sccsid[] = "@(#)swab.c 8.1 (Berkeley) 6/4/93"; -#endif /* LIBC_SCCS and not lint */ -#include <sys/cdefs.h> -__FBSDID("$FreeBSD$"); - #include <unistd.h> +#include <sys/endian.h> void swab(const void * __restrict from, void * __restrict to, ssize_t len) { - unsigned long temp; - int n; - char *fp, *tp; + const uint16_t *f __aligned(1) = from; + uint16_t *t __aligned(1) = to; - if (len <= 0) - return; - n = len >> 1; - fp = (char *)from; - tp = (char *)to; -#define STEP temp = *fp++,*tp++ = *fp++,*tp++ = temp - /* round to multiple of 8 */ - for (; n & 0x7; --n) - STEP; - for (n >>= 3; n > 0; --n) { - STEP; STEP; STEP; STEP; - STEP; STEP; STEP; STEP; + /* + * POSIX says overlapping copy behavior is undefined, however many + * applications assume the old FreeBSD and current GNU libc behavior + * that will swap the bytes correctly when from == to. Reading both bytes + * and swapping them before writing them back accomplishes this. + */ + while (len > 1) { + *t++ = bswap16(*f++); + len -= 2; } } |