githubmirror/file

src/swap.c
101 строка3 KB
Christos Zoulas
Add LE/BE GUID
19 апр 2026, 22:56
19 апр 2026, 22:56797a275
/*
 * Copyright (c) Ian F. Darwin 1986-1995.
 * Software written by Ian F. Darwin and others;
 * maintained 1995-present by Christos Zoulas and others.
 *
 * 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 immediately at the beginning of the file, without modification,
 *    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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */
/*
 * apprentice - make one pass through /etc/magic, learning its secrets.
 */

#include "file.h"

#ifndef	lint
FILE_RCSID("@(#)$File: swap.c,v 1.1 2026/04/19 19:56:49 christos Exp $")
#endif	/* lint */

#include "swap.h"

#if !defined(HAVE_BYTESWAP_H) && !defined(HAVE_SYS_BSWAP_H)
/*
 * swap a short
 */
file_protected uint16_t
file_swap2(uint16_t sv)
{
	uint16_t rv;
	uint8_t *s = RCAST(uint8_t *, RCAST(void *, &sv));
	uint8_t *d = RCAST(uint8_t *, RCAST(void *, &rv));
	d[0] = s[1];
	d[1] = s[0];
	return rv;
}

/*
 * swap an int
 */
file_protected uint32_t
file_swap4(uint32_t sv)
{
	uint32_t rv;
	uint8_t *s = RCAST(uint8_t *, RCAST(void *, &sv));
	uint8_t *d = RCAST(uint8_t *, RCAST(void *, &rv));
	d[0] = s[3];
	d[1] = s[2];
	d[2] = s[1];
	d[3] = s[0];
	return rv;
}

/*
 * swap a quad
 */
file_protected uint64_t
file_swap8(uint64_t sv)
{
	uint64_t rv;
	uint8_t *s = RCAST(uint8_t *, RCAST(void *, &sv));
	uint8_t *d = RCAST(uint8_t *, RCAST(void *, &rv));
# if 0
	d[0] = s[3];
	d[1] = s[2];
	d[2] = s[1];
	d[3] = s[0];
	d[4] = s[7];
	d[5] = s[6];
	d[6] = s[5];
	d[7] = s[4];
# else
	d[0] = s[7];
	d[1] = s[6];
	d[2] = s[5];
	d[3] = s[4];
	d[4] = s[3];
	d[5] = s[2];
	d[6] = s[1];
	d[7] = s[0];
# endif
	return rv;
}
#endif