FreeBSD/Linux Kernel Cross Reference
sys/sys/_endian.h

     /*-
      * 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.
     */
    
    #ifndef _SYS__ENDIAN_H_
    #define _SYS__ENDIAN_H_
    
    #if !defined(_MACHINE_ENDIAN_H_) && !defined(_BYTESWAP_H_) && !defined(_ENDIAN_H_)
    #error "sys/_endian.h should not be included directly"
    #endif
    
    /* BSD Compatiblity */
    #define _BYTE_ORDER     __BYTE_ORDER__
    
    /*
     * Definitions for byte order, according to byte significance from low
     * address to high.
     */
    #define _LITTLE_ENDIAN  __ORDER_LITTLE_ENDIAN__ /* LSB first: 1234 */
    #define _BIG_ENDIAN     __ORDER_BIG_ENDIAN__    /* MSB first: 4321 */
    #define _PDP_ENDIAN     __ORDER_PDP_ENDIAN__    /* LSB first in word,
                                                     * MSW first in long: 3412 */
    
    /*
     * Define the order of 32-bit words in 64-bit words.
     */
    #if _BYTE_ORDER == _LITTLE_ENDIAN
    #define _QUAD_HIGHWORD  1
    #define _QUAD_LOWWORD   0
    #elif _BYTE_ORDER == _BIG_ENDIAN
    #define _QUAD_HIGHWORD  0
    #define _QUAD_LOWWORD   1
    #else
    #error "Unsupported endian"
    #endif
    
    /*
     * 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
    
    /* bswap primitives, based on compiler builtins */
    #define __bswap16(x)    __builtin_bswap16(x)
    #define __bswap32(x)    __builtin_bswap32(x)
    #define __bswap64(x)    __builtin_bswap64(x)
    
    #if _BYTE_ORDER == _LITTLE_ENDIAN
    #define __ntohl(x)      (__bswap32(x))
    #define __ntohs(x)      (__bswap16(x))
    #define __htonl(x)      (__bswap32(x))
    #define __htons(x)      (__bswap16(x))
    #elif _BYTE_ORDER == _BIG_ENDIAN
    #define __htonl(x)      ((__uint32_t)(x))
    #define __htons(x)      ((__uint16_t)(x))
    #define __ntohl(x)      ((__uint32_t)(x))
    #define __ntohs(x)      ((__uint16_t)(x))
    #endif
    
    /*
     * Host to big endian, host to little endian, big endian to host, and little
     * endian to host byte order functions as detailed in byteorder(9).
     */
    #if _BYTE_ORDER == _LITTLE_ENDIAN
    #define htobe16(x)      __bswap16((x))
    #define htobe32(x)      __bswap32((x))
    #define htobe64(x)      __bswap64((x))
   #define htole16(x)      ((uint16_t)(x))
   #define htole32(x)      ((uint32_t)(x))
   #define htole64(x)      ((uint64_t)(x))
   
   #define be16toh(x)      __bswap16((x))
   #define be32toh(x)      __bswap32((x))
   #define be64toh(x)      __bswap64((x))
   #define le16toh(x)      ((uint16_t)(x))
   #define le32toh(x)      ((uint32_t)(x))
   #define le64toh(x)      ((uint64_t)(x))
   #else /* _BYTE_ORDER != _LITTLE_ENDIAN */
   #define htobe16(x)      ((uint16_t)(x))
   #define htobe32(x)      ((uint32_t)(x))
   #define htobe64(x)      ((uint64_t)(x))
   #define htole16(x)      __bswap16((x))
   #define htole32(x)      __bswap32((x))
   #define htole64(x)      __bswap64((x))
   
   #define be16toh(x)      ((uint16_t)(x))
   #define be32toh(x)      ((uint32_t)(x))
   #define be64toh(x)      ((uint64_t)(x))
   #define le16toh(x)      __bswap16((x))
   #define le32toh(x)      __bswap32((x))
   #define le64toh(x)      __bswap64((x))
   #endif /* _BYTE_ORDER == _LITTLE_ENDIAN */
   
   #endif /* _SYS__ENDIAN_H_ */

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