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byte_swap.h revision 1.4 
      1 /*	$NetBSD: byte_swap.h,v 1.4 2001/11/02 05:17:59 lukem Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1998 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Charles M. Hannum.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #ifndef _I386_BYTE_SWAP_H_
     40 #define	_I386_BYTE_SWAP_H_
     41 
     42 #if defined(_KERNEL_OPT)
     43 #include "opt_cputype.h"
     44 #endif
     45 
     46 
     47 static __inline u_int32_t __byte_swap_long_variable(u_int32_t);
     48 static __inline u_int16_t __byte_swap_word_variable(u_int16_t);
     49 
     50 static __inline u_int32_t
     51 __byte_swap_long_variable(u_int32_t x)
     52 {
     53 	__asm __volatile (
     54 #if defined(_KERNEL) && !defined(_LKM) && !defined(I386_CPU)
     55 	    "bswap %1"
     56 #else
     57 	    "rorw $8, %w1\n\trorl $16, %1\n\trorw $8, %w1"
     58 #endif
     59 	    : "=r" (x) : "0" (x));
     60 	return x;
     61 }
     62 
     63 static __inline u_int16_t
     64 __byte_swap_word_variable(u_int16_t x)
     65 {
     66 	__asm __volatile ("rorw $8, %w1" : "=r" (x) : "0" (x));
     67 	return x;
     68 }
     69 
     70 #ifdef __OPTIMIZE__
     71 
     72 #define	__byte_swap_long_constant(x) \
     73 	((((x) & 0xff000000) >> 24) | \
     74 	 (((x) & 0x00ff0000) >>  8) | \
     75 	 (((x) & 0x0000ff00) <<  8) | \
     76 	 (((x) & 0x000000ff) << 24))
     77 #define	__byte_swap_word_constant(x) \
     78 	((((x) & 0xff00) >> 8) | \
     79 	 (((x) & 0x00ff) << 8))
     80 #define	__byte_swap_long(x) \
     81 	(__builtin_constant_p((x)) ? \
     82 	 __byte_swap_long_constant(x) : __byte_swap_long_variable(x))
     83 #define	__byte_swap_word(x) \
     84 	(__builtin_constant_p((x)) ? \
     85 	 __byte_swap_word_constant(x) : __byte_swap_word_variable(x))
     86 
     87 #else /* __OPTIMIZE__ */
     88 
     89 #define	__byte_swap_long(x)	__byte_swap_long_variable(x)
     90 #define	__byte_swap_word(x)	__byte_swap_word_variable(x)
     91 
     92 #endif /* __OPTIMIZE__ */
     93 
     94 #endif /* !_I386_BYTE_SWAP_H_ */
     95