xref: /freebsd/sys/x86/include/endian.h (revision 51369649b03ece2aed3eb61b0c8214b9aa5b2fa2)

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1987, 1991 Regents of the University of California.
 * All rights reserved.
 *
 * 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.
 *
 *	@(#)endian.h	7.8 (Berkeley) 4/3/91
 * $FreeBSD$
 */

#ifndef _MACHINE_ENDIAN_H_
#define	_MACHINE_ENDIAN_H_

#include <sys/cdefs.h>
#include <sys/_types.h>

/*
 * Define the order of 32-bit words in 64-bit words.
 */
#define	_QUAD_HIGHWORD 1
#define	_QUAD_LOWWORD 0

/*
 * Definitions for byte order, according to byte significance from low
 * address to high.
 */
#define	_LITTLE_ENDIAN	1234	/* LSB first: i386, vax */
#define	_BIG_ENDIAN	4321	/* MSB first: 68000, ibm, net */
#define	_PDP_ENDIAN	3412	/* LSB first in word, MSW first in long */

#define	_BYTE_ORDER	_LITTLE_ENDIAN

/*
 * Deprecated variants that don't have enough underscores to be useful in more
 * strict namespaces.
 */
#if __BSD_VISIBLE
#define	LITTLE_ENDIAN	_LITTLE_ENDIAN
#define	BIG_ENDIAN	_BIG_ENDIAN
#define	PDP_ENDIAN	_PDP_ENDIAN
#define	BYTE_ORDER	_BYTE_ORDER
#endif

#define	__bswap16_gen(x)	(__uint16_t)((x) << 8 | (x) >> 8)
#define	__bswap32_gen(x)		\
	(((__uint32_t)__bswap16((x) & 0xffff) << 16) | __bswap16((x) >> 16))
#define	__bswap64_gen(x)		\
	(((__uint64_t)__bswap32((x) & 0xffffffff) << 32) | __bswap32((x) >> 32))

#ifdef __GNUCLIKE_BUILTIN_CONSTANT_P
#define	__bswap16(x)				\
	((__uint16_t)(__builtin_constant_p(x) ?	\
	    __bswap16_gen((__uint16_t)(x)) : __bswap16_var(x)))
#define	__bswap32(x)			\
	(__builtin_constant_p(x) ?	\
	    __bswap32_gen((__uint32_t)(x)) : __bswap32_var(x))
#define	__bswap64(x)			\
	(__builtin_constant_p(x) ?	\
	    __bswap64_gen((__uint64_t)(x)) : __bswap64_var(x))
#else
/* XXX these are broken for use in static initializers. */
#define	__bswap16(x)	__bswap16_var(x)
#define	__bswap32(x)	__bswap32_var(x)
#define	__bswap64(x)	__bswap64_var(x)
#endif

/* These are defined as functions to avoid multiple evaluation of x. */

static __inline __uint16_t
__bswap16_var(__uint16_t _x)
{

	return (__bswap16_gen(_x));
}

static __inline __uint32_t
__bswap32_var(__uint32_t _x)
{

#ifdef __GNUCLIKE_ASM
	__asm("bswap %0" : "+r" (_x));
	return (_x);
#else
	return (__bswap32_gen(_x));
#endif
}

static __inline __uint64_t
__bswap64_var(__uint64_t _x)
{

#if defined(__amd64__) && defined(__GNUCLIKE_ASM)
	__asm("bswap %0" : "+r" (_x));
	return (_x);
#else
	/*
	 * It is important for the optimizations that the following is not
	 * really generic, but expands to 2 __bswap32_var()'s.
	 */
	return (__bswap64_gen(_x));
#endif
}

#define	__htonl(x)	__bswap32(x)
#define	__htons(x)	__bswap16(x)
#define	__ntohl(x)	__bswap32(x)
#define	__ntohs(x)	__bswap16(x)

#endif /* !_MACHINE_ENDIAN_H_ */