This is xnu-8019. See this file in:
/*
 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
 */
/*
 * Copyright 1995 NeXT Computer, Inc. All rights reserved.
 */
/*
 * Copyright (c) 1987, 1991, 1993
 *	The 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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	8.1 (Berkeley) 6/11/93
 */

#ifndef _ARM__ENDIAN_H_
#define _ARM__ENDIAN_H_

#if defined (__arm__) || defined (__arm64__)

#include <sys/cdefs.h>
/*
 * Define _NOQUAD if the compiler does NOT support 64-bit integers.
 */
/* #define _NOQUAD */

/*
 * 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 __DARWIN_LITTLE_ENDIAN  1234    /* LSB first: i386, vax */
#define __DARWIN_BIG_ENDIAN     4321    /* MSB first: 68000, ibm, net */
#define __DARWIN_PDP_ENDIAN     3412    /* LSB first in word, MSW first in long */

#define __DARWIN_BYTE_ORDER     __DARWIN_LITTLE_ENDIAN

#if     defined(KERNEL) || (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE))

#define LITTLE_ENDIAN   __DARWIN_LITTLE_ENDIAN
#define BIG_ENDIAN      __DARWIN_BIG_ENDIAN
#define PDP_ENDIAN      __DARWIN_PDP_ENDIAN

#define BYTE_ORDER      __DARWIN_BYTE_ORDER

#include <sys/_endian.h>

#endif /* defined(KERNEL) || (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE)) */
#endif /* defined (__arm__) || defined (__arm64__) */
#endif /* !_ARM__ENDIAN_H_ */