The C and C++ Include Header Files

/usr/include/x86_64-linux-gnu/bits/endian.h


$ cat -n /usr/include/x86_64-linux-gnu/bits/endian.h

     1	/* Endian macros for string.h functions
     2	   Copyright (C) 1992-2024 Free Software Foundation, Inc.
     3	   This file is part of the GNU C Library.
     4	
     5	   The GNU C Library is free software; you can redistribute it and/or
     6	   modify it under the terms of the GNU Lesser General Public
     7	   License as published by the Free Software Foundation; either
     8	   version 2.1 of the License, or (at your option) any later version.
     9	
    10	   The GNU C Library is distributed in the hope that it will be useful,
    11	   but WITHOUT ANY WARRANTY; without even the implied warranty of
    12	   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13	   Lesser General Public License for more details.
    14	
    15	   You should have received a copy of the GNU Lesser General Public
    16	   License along with the GNU C Library; if not, see
    17	   <http://www.gnu.org/licenses/>.  */
    18	
    19	#ifndef _BITS_ENDIAN_H
    20	#define _BITS_ENDIAN_H 1
    21	
    22	/* Definitions for byte order, according to significance of bytes,
    23	   from low addresses to high addresses.  The value is what you get by
    24	   putting '4' in the most significant byte, '3' in the second most
    25	   significant byte, '2' in the second least significant byte, and '1'
    26	   in the least significant byte, and then writing down one digit for
    27	   each byte, starting with the byte at the lowest address at the left,
    28	   and proceeding to the byte with the highest address at the right.  */
    29	
    30	#define	__LITTLE_ENDIAN	1234
    31	#define	__BIG_ENDIAN	4321
    32	#define	__PDP_ENDIAN	3412
    33	
    34	/* This file defines `__BYTE_ORDER' for the particular machine.  */
    35	#include <bits/endianness.h>
    36	
    37	/* Some machines may need to use a different endianness for floating point
    38	   values.  */
    39	#ifndef __FLOAT_WORD_ORDER
    40	# define __FLOAT_WORD_ORDER __BYTE_ORDER
    41	#endif
    42	
    43	#if __BYTE_ORDER == __LITTLE_ENDIAN
    44	# define __LONG_LONG_PAIR(HI, LO) LO, HI
    45	#elif __BYTE_ORDER == __BIG_ENDIAN
    46	# define __LONG_LONG_PAIR(HI, LO) HI, LO
    47	#endif
    48	
    49	#endif /* bits/endian.h */