glibc (2.38)

(root)/
include/
bits/
endianness.h
       1  #ifndef _BITS_ENDIANNESS_H
       2  #define _BITS_ENDIANNESS_H 1
       3  
       4  #ifndef _BITS_ENDIAN_H
       5  # error "Never use <bits/endianness.h> directly; include <endian.h> instead."
       6  #endif
       7  
       8  /* i386/x86_64 are little-endian.  */
       9  #define __BYTE_ORDER __LITTLE_ENDIAN
      10  
      11  #endif /* bits/endianness.h */