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byte_swap.h revision 1.3.2.3 
      1 /*	$NetBSD: byte_swap.h,v 1.3.2.3 2002/11/18 01:16:24 he Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1997, 1999, 2002 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, Neil A. Carson, and Jason R. Thorpe.
      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 _ARM_BYTE_SWAP_H_
     40 #define	_ARM_BYTE_SWAP_H_
     41 
     42 #include <sys/types.h>
     43 
     44 static __inline u_int32_t
     45 __byte_swap_32_variable(u_int32_t v)
     46 {
     47 	u_int32_t t1;
     48 
     49 	t1 = v ^ ((v << 16) | (v >> 16));
     50 	t1 &= 0xff00ffff;
     51 	v = (v >> 8) | (v << 24);
     52 	v ^= (t1 >> 8);
     53 
     54 	return (v);
     55 }
     56 
     57 static __inline u_int16_t
     58 __byte_swap_16_variable(u_int16_t v)
     59 {
     60 
     61 	__asm __volatile(
     62 		"mov	%0, %1, ror #8\n"
     63 		"orr	%0, %0, %0, lsr #16\n"
     64 		"bic	%0, %0, %0, lsl #16"
     65 	: "=r" (v)
     66 	: "0" (v));
     67 
     68 	return (v);
     69 }
     70 
     71 #ifdef __OPTIMIZE__
     72 
     73 #define __byte_swap_32_constant(x)	\
     74 	((((x) & 0xff000000) >> 24) |	\
     75 	 (((x) & 0x00ff0000) >>  8) |	\
     76 	 (((x) & 0x0000ff00) <<  8) |	\
     77 	 (((x) & 0x000000ff) << 24))
     78 
     79 #define	__byte_swap_16_constant(x)	\
     80 	((((x) & 0xff00) >> 8) |	\
     81 	 (((x) & 0x00ff) << 8))
     82 
     83 #define	__byte_swap_32(x)		\
     84 	(__builtin_constant_p((x)) ?	\
     85 	 __byte_swap_32_constant(x) :	__byte_swap_32_variable(x))
     86 
     87 #define	__byte_swap_16(x)		\
     88 	(__builtin_constant_p((x)) ?	\
     89 	 __byte_swap_16_constant(x) : __byte_swap_16_variable(x))
     90 
     91 #else
     92 
     93 #define	__byte_swap_32(x)	__byte_swap_32_variable(x)
     94 #define	__byte_swap_16(x)	__byte_swap_16_variable(x)
     95 
     96 #endif /* __OPTIMIZE__ */
     97 
     98 #endif /* _ARM_BYTE_SWAP_H_ */
     99