FreeBSD/Linux Kernel Cross Reference
sys/arm64/include/endian.h

     /*-
      * Copyright (c) 2001 David E. O'Brien
      *
      * 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.
     *
     *      @(#)endian.h    8.1 (Berkeley) 6/10/93
     * $NetBSD: endian.h,v 1.7 1999/08/21 05:53:51 simonb Exp $
     * $FreeBSD: releng/11.2/sys/arm64/include/endian.h 280364 2015-03-23 11:54:56Z andrew $
     */
    
    #ifndef _MACHINE_ENDIAN_H_
    #define _MACHINE_ENDIAN_H_
    
    #include <sys/_types.h>
    
    /*
     * Definitions for byte order, according to byte significance from low
     * address to high.
     */
    #define _LITTLE_ENDIAN  1234    /* LSB first: i386, vax */
    #define _BIG_ENDIAN     4321    /* MSB first: 68000, ibm, net */
    #define _PDP_ENDIAN     3412    /* LSB first in word, MSW first in long */
    
    #define _BYTE_ORDER     _LITTLE_ENDIAN
    
    #if __BSD_VISIBLE
    #define LITTLE_ENDIAN   _LITTLE_ENDIAN
    #define BIG_ENDIAN      _BIG_ENDIAN
    #define PDP_ENDIAN      _PDP_ENDIAN
    #define BYTE_ORDER      _BYTE_ORDER
    #endif
    
    #define _QUAD_HIGHWORD  1
    #define _QUAD_LOWWORD 0
    #define __ntohl(x)        (__bswap32(x))
    #define __ntohs(x)        (__bswap16(x))
    #define __htonl(x)        (__bswap32(x))
    #define __htons(x)        (__bswap16(x))
    
    static __inline __uint64_t
    __bswap64(__uint64_t x)
    {
            __uint64_t ret;
    
            __asm __volatile("rev %0, %1\n"
                             : "=&r" (ret), "+r" (x));
            
            return (ret);
    }
    
    static __inline __uint32_t
    __bswap32_var(__uint32_t v)
    {
            __uint32_t ret;
    
            __asm __volatile("rev32 %x0, %x1\n"
                             : "=&r" (ret), "+r" (v));
            
            return (ret);
    }
    
    static __inline __uint16_t
    __bswap16_var(__uint16_t v)
    {
            __uint32_t ret;
    
            __asm __volatile("rev16 %w0, %w1\n"
                             : "=&r" (ret), "+r" (v));
    
            return ((__uint16_t)ret);
    }               
    
    #ifdef __OPTIMIZE__
    
    #define __bswap32_constant(x)   \
        ((((x) & 0xff000000U) >> 24) |      \
         (((x) & 0x00ff0000U) >>  8) |      \
        (((x) & 0x0000ff00U) <<  8) |      \
        (((x) & 0x000000ffU) << 24))
   
   #define __bswap16_constant(x)   \
       ((((x) & 0xff00) >> 8) |            \
        (((x) & 0x00ff) << 8))
   
   #define __bswap16(x)    \
       ((__uint16_t)(__builtin_constant_p(x) ?     \
        __bswap16_constant(x) :                    \
        __bswap16_var(x)))
   
   #define __bswap32(x)    \
       ((__uint32_t)(__builtin_constant_p(x) ?     \
        __bswap32_constant(x) :                    \
        __bswap32_var(x)))
   
   #else
   #define __bswap16(x)    __bswap16_var(x)
   #define __bswap32(x)    __bswap32_var(x)
   
   #endif /* __OPTIMIZE__ */
   #endif /* !_MACHINE_ENDIAN_H_ */

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