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The C and C++ Include Header Files

/usr/include/linux/patchkey.h


$ cat -n /usr/include/linux/patchkey.h

     1	/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
     2	/*
     3	 * <linux/patchkey.h> -- definition of _PATCHKEY macro
     4	 *
     5	 * Copyright (C) 2005 Stuart Brady
     6	 *
     7	 * This exists because awe_voice.h defined its own _PATCHKEY and it wasn't
     8	 * clear whether removing this would break anything in userspace.
     9	 *
    10	 * Do not include this file directly.  Please use <sys/soundcard.h> instead.
    11	 * For kernel code, use <linux/soundcard.h>
    12	 */
    13	
    14	#ifndef _LINUX_PATCHKEY_H_INDIRECT
    15	#error "patchkey.h included directly"
    16	#endif
    17	
    18	#ifndef _LINUX_PATCHKEY_H
    19	#define _LINUX_PATCHKEY_H
    20	
    21	/* Endian macros. */
    22	#  include <endian.h>
    23	
    24	#if defined(__BYTE_ORDER)
    25	#  if __BYTE_ORDER == __BIG_ENDIAN
    26	#    define _PATCHKEY(id) (0xfd00|id)
    27	#  elif __BYTE_ORDER == __LITTLE_ENDIAN
    28	#    define _PATCHKEY(id) ((id<<8)|0x00fd)
    29	#  else
    30	#    error "could not determine byte order"
    31	#  endif
    32	#endif
    33	
    34	#endif /* _LINUX_PATCHKEY_H */