sys/arch/arm/include/byte_swap.h

   1 /*      $NetBSD: byte_swap.h,v 1.13 2013/01/28 06:16:05 matt 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 _LOCORE
  36
  37 #if defined(_ARM_ARCH_6) || defined(_ARM_ARCH_7)
  38
  39 #define BSWAP16(_src, _dst, _tmp)               \
  40         rev16   _dst, _src
  41 #define BSWAP32(_src, _dst, _tmp)               \
  42         rev     _dst, _src
  43
  44 #else
  45
  46 #define BSWAP16(_src, _dst, _tmp)               \
  47         mov     _tmp, _src, ror #8              ;\
  48         orr     _tmp, _tmp, _tmp, lsr #16       ;\
  49         bic     _dst, _tmp, _tmp, lsl #16
  50
  51 #define BSWAP32(_src, _dst, _tmp)               \
  52         eor     _tmp, _src, _src, ror #16       ;\
  53         bic     _tmp, _tmp, #0x00FF0000         ;\
  54         mov     _dst, _src, ror #8              ;\
  55         eor     _dst, _dst, _tmp, lsr #8
  56
  57 #endif
  58
  59
  60 #else
  61
  62 #ifdef __GNUC__
  63 #include <sys/types.h>
  64 __BEGIN_DECLS
  65
  66 #define __BYTE_SWAP_U32_VARIABLE __byte_swap_u32_variable
  67 static __inline uint32_t
  68 __byte_swap_u32_variable(uint32_t v)
  69 {
  70         uint32_t t1;
  71
  72 #ifdef _ARM_ARCH_6
  73         if (!__builtin_constant_p(v)) {
  74                 __asm("rev\t%0, %1" : "=r" (v) : "0" (v));
  75                 return v;
  76         }
  77 #endif
  78
  79         t1 = v ^ ((v << 16) | (v >> 16));
  80         t1 &= 0xff00ffffU;
  81         v = (v >> 8) | (v << 24);
  82         v ^= (t1 >> 8);
  83
  84         return (v);
  85 }
  86
  87 #define __BYTE_SWAP_U16_VARIABLE __byte_swap_u16_variable
  88 static __inline uint16_t
  89 __byte_swap_u16_variable(uint16_t v)
  90 {
  91
  92 #ifdef _ARM_ARCH_6
  93         if (!__builtin_constant_p(v)) {
  94                 uint32_t v32 = v;
  95                 __asm("rev16\t%0, %1" : "=r" (v32) : "0" (v32));
  96                 return v32;
  97         }
  98 #elif !defined(__thumb__) && 0  /* gcc produces decent code for this */
  99         if (!__builtin_constant_p(v)) {
 100                 uint32_t v0 = v;
 101                 __asm volatile(
 102                         "mov    %0, %1, ror #8\n"
 103                         "orr    %0, %0, %0, lsr #16\n"
 104                         "bic    %0, %0, %0, lsl #16"
 105                 : "=&r" (v0)
 106                 : "0" (v0));
 107                 return v0;
 108         }
 109 #endif
 110         v &= 0xffff;
 111         v = (v >> 8) | (v << 8);
 112
 113         return (v);
 114 }
 115
 116 __END_DECLS
 117 #endif
 118
 119 #endif  /* _LOCORE */
 120
 121 #endif /* _ARM_BYTE_SWAP_H_ */