FreeBSD/Linux Kernel Cross Reference
sys/i386/include/endian.h

     /*-
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. 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    7.8 (Berkeley) 4/3/91
     * $FreeBSD: releng/5.2/sys/i386/include/endian.h 120344 2003-09-22 21:46:47Z peter $
     */
    
    #ifndef _MACHINE_ENDIAN_H_
    #define _MACHINE_ENDIAN_H_
    
    #include <sys/cdefs.h>
    #include <sys/_types.h>
    
    /*
     * Define the order of 32-bit words in 64-bit words.
     */
    #define _QUAD_HIGHWORD 1
    #define _QUAD_LOWWORD 0
    
    /*
     * 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
    
    /*
     * 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
    
    #ifdef __GNUC__
    
    #define __word_swap_int_var(x) \
    __extension__ ({ register __uint32_t __X = (x); \
       __asm ("rorl $16, %0" : "+r" (__X)); \
       __X; })
    
    #ifdef __OPTIMIZE__
    
    #define __word_swap_int_const(x) \
            ((((x) & 0xffff0000) >> 16) | \
             (((x) & 0x0000ffff) << 16))
    #define __word_swap_int(x) (__builtin_constant_p(x) ? \
            __word_swap_int_const(x) : __word_swap_int_var(x))
    
    #else   /* __OPTIMIZE__ */
    
    #define __word_swap_int(x) __word_swap_int_var(x)
    
    #endif  /* __OPTIMIZE__ */
    
    #if defined(_KERNEL) && (defined(I486_CPU) || defined(I586_CPU) || defined(I686_CPU)) && !defined(I386_CPU)
    
    #define __byte_swap_int_var(x) \
    __extension__ ({ register __uint32_t __X = (x); \
       __asm ("bswap %0" : "+r" (__X)); \
       __X; })
    #else
    
    #define __byte_swap_int_var(x) \
   __extension__ ({ register __uint32_t __X = (x); \
      __asm ("xchgb %h0, %b0\n\trorl $16, %0\n\txchgb %h0, %b0" \
          : "+q" (__X)); \
      __X; })
   #endif
   
   #ifdef __OPTIMIZE__
   
   #define __byte_swap_int_const(x) \
           ((((x) & 0xff000000) >> 24) | \
            (((x) & 0x00ff0000) >>  8) | \
            (((x) & 0x0000ff00) <<  8) | \
            (((x) & 0x000000ff) << 24))
   #define __byte_swap_int(x) (__builtin_constant_p(x) ? \
           __byte_swap_int_const(x) : __byte_swap_int_var(x))
   
   #else   /* __OPTIMIZE__ */
   
   #define __byte_swap_int(x) __byte_swap_int_var(x)
   
   #endif  /* __OPTIMIZE__ */
   
   #define __byte_swap_word_var(x) \
   __extension__ ({ register __uint16_t __X = (x); \
      __asm ("xchgb %h0, %b0" : "+q" (__X)); \
      __X; })
   
   #ifdef __OPTIMIZE__
   
   #define __byte_swap_word_const(x) \
           ((((x) & 0xff00) >> 8) | \
            (((x) & 0x00ff) << 8))
   
   #define __byte_swap_word(x) (__builtin_constant_p(x) ? \
           __byte_swap_word_const(x) : __byte_swap_word_var(x))
   
   #else   /* __OPTIMIZE__ */
   
   #define __byte_swap_word(x) __byte_swap_word_var(x)
   
   #endif  /* __OPTIMIZE__ */
   
   static __inline __uint64_t
   __bswap64(__uint64_t _x)
   {
   
           return ((_x >> 56) | ((_x >> 40) & 0xff00) | ((_x >> 24) & 0xff0000) |
               ((_x >> 8) & 0xff000000) | ((_x << 8) & ((__uint64_t)0xff << 32)) |
               ((_x << 24) & ((__uint64_t)0xff << 40)) |
               ((_x << 40) & ((__uint64_t)0xff << 48)) | ((_x << 56)));
   }
   
   static __inline __uint32_t
   __bswap32(__uint32_t _x)
   {
   
           return (__byte_swap_int(_x));
   }
   
   static __inline __uint16_t
   __bswap16(__uint16_t _x)
   {
   
           return (__byte_swap_word(_x));
   }
   
   #define __htonl(x)      __bswap32(x)
   #define __htons(x)      __bswap16(x)
   #define __ntohl(x)      __bswap32(x)
   #define __ntohs(x)      __bswap16(x)
   
   #else /* !__GNUC__ */
   
   /*
    * No optimizations are available for this compiler.  Fall back to
    * non-optimized functions by defining the constant usually used to prevent
    * redefinition.
    */
   #define _BYTEORDER_FUNC_DEFINED
   
   #endif /* __GNUC__ */
   
   #endif /* !_MACHINE_ENDIAN_H_ */

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