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byte_swap.h revision 1.8.40.1 
      1 /*	$NetBSD: byte_swap.h,v 1.8.40.1 2012/09/13 20:28:15 riz 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  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef _ARM_BYTE_SWAP_H_
     33 #define	_ARM_BYTE_SWAP_H_
     34 
     35 #ifdef __GNUC__
     36 #include <sys/types.h>
     37 __BEGIN_DECLS
     38 
     39 #define	__BYTE_SWAP_U32_VARIABLE __byte_swap_u32_variable
     40 static __inline uint32_t
     41 __byte_swap_u32_variable(uint32_t v)
     42 {
     43 	uint32_t t1;
     44 
     45 #ifdef _ARM_ARCH_6
     46 	if (!__builtin_constant_p(v)) {
     47 		__asm("rev\t%0, %1" : "=r" (v) : "0" (v));
     48 		return v;
     49 	}
     50 #endif
     51 
     52 	t1 = v ^ ((v << 16) | (v >> 16));
     53 	t1 &= 0xff00ffffU;
     54 	v = (v >> 8) | (v << 24);
     55 	v ^= (t1 >> 8);
     56 
     57 	return (v);
     58 }
     59 
     60 #define	__BYTE_SWAP_U16_VARIABLE __byte_swap_u16_variable
     61 static __inline uint16_t
     62 __byte_swap_u16_variable(uint16_t v)
     63 {
     64 
     65 #ifdef _ARM_ARCH_6
     66 	if (!__builtin_constant_p(v)) {
     67 		__asm("rev16\t%0, %1" : "=r" (v) : "0" (v));
     68 		return v;
     69 	}
     70 #elif !defined(__thumb__) && 0	/* gcc produces decent code for this */
     71 	if (!__builtin_constant_p(v)) {
     72 		uint32_t v0 = v;
     73 		__asm volatile(
     74 			"mov	%0, %1, ror #8\n"
     75 			"orr	%0, %0, %0, lsr #16\n"
     76 			"bic	%0, %0, %0, lsl #16"
     77 		: "=&r" (v0)
     78 		: "0" (v0));
     79 		return v0;
     80 	}
     81 #endif
     82 	v &= 0xffff;
     83 	v = (v >> 8) | (v << 8);
     84 
     85 	return (v);
     86 }
     87 
     88 __END_DECLS
     89 #endif
     90 
     91 
     92 #endif /* _ARM_BYTE_SWAP_H_ */
     93