src/sim/byteswap.hh

   1 /*
   2  * Copyright (c) 2004 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 //The purpose of this file is to provide endainness conversion utility
  30 //functions. Depending on the endianness of the guest system, either
  31 //the LittleEndianGuest or BigEndianGuest namespace is used.
  32
  33 #ifndef __SIM_BYTE_SWAP_HH__
  34 #define __SIM_BYTE_SWAP_HH__
  35
  36 #include "base/logging.hh"
  37 #include "base/types.hh"
  38
  39 // This lets us figure out what the byte order of the host system is
  40 #if defined(__linux__)
  41 #include <endian.h>
  42 // If this is a linux system, lets used the optimized definitions if they exist.
  43 // If one doesn't exist, we pretty much get what is listed below, so it all
  44 // works out
  45 #include <byteswap.h>
  46 #elif defined (__sun)
  47 #include <sys/isa_defs.h>
  48 #else
  49 #include <machine/endian.h>
  50 #endif
  51
  52 #if defined(__APPLE__)
  53 #include <libkern/OSByteOrder.h>
  54 #endif
  55
  56 //These functions actually perform the swapping for parameters
  57 //of various bit lengths
  58 inline uint64_t
  59 swap_byte64(uint64_t x)
  60 {
  61 #if defined(__linux__)
  62     return bswap_64(x);
  63 #elif defined(__APPLE__)
  64     return OSSwapInt64(x);
  65 #else
  66     return  (uint64_t)((((uint64_t)(x) & 0xff) << 56) |
  67             ((uint64_t)(x) & 0xff00ULL) << 40 |
  68             ((uint64_t)(x) & 0xff0000ULL) << 24 |
  69             ((uint64_t)(x) & 0xff000000ULL) << 8 |
  70             ((uint64_t)(x) & 0xff00000000ULL) >> 8 |
  71             ((uint64_t)(x) & 0xff0000000000ULL) >> 24 |
  72             ((uint64_t)(x) & 0xff000000000000ULL) >> 40 |
  73             ((uint64_t)(x) & 0xff00000000000000ULL) >> 56) ;
  74 #endif
  75 }
  76
  77 inline uint32_t
  78 swap_byte32(uint32_t x)
  79 {
  80 #if defined(__linux__)
  81     return bswap_32(x);
  82 #elif defined(__APPLE__)
  83     return OSSwapInt32(x);
  84 #else
  85     return  (uint32_t)(((uint32_t)(x) & 0xff) << 24 |
  86             ((uint32_t)(x) & 0xff00) << 8 | ((uint32_t)(x) & 0xff0000) >> 8 |
  87             ((uint32_t)(x) & 0xff000000) >> 24);
  88 #endif
  89 }
  90
  91 inline uint16_t
  92 swap_byte16(uint16_t x)
  93 {
  94 #if defined(__linux__)
  95     return bswap_16(x);
  96 #elif defined(__APPLE__)
  97     return OSSwapInt16(x);
  98 #else
  99     return (uint16_t)(((uint16_t)(x) & 0xff) << 8 |
 100                       ((uint16_t)(x) & 0xff00) >> 8);
 101 #endif
 102 }
 103
 104 // This function lets the compiler figure out how to call the
 105 // swap_byte functions above for different data types.  Since the
 106 // sizeof() values are known at compile time, it should inline to a
 107 // direct call to the right swap_byteNN() function.
 108 template <typename T>
 109 inline T swap_byte(T x) {
 110     if (sizeof(T) == 8)
 111         return swap_byte64((uint64_t)x);
 112     else if (sizeof(T) == 4)
 113         return swap_byte32((uint32_t)x);
 114     else if (sizeof(T) == 2)
 115         return swap_byte16((uint16_t)x);
 116     else if (sizeof(T) == 1)
 117         return x;
 118     else
 119         panic("Can't byte-swap values larger than 64 bits");
 120 }
 121
 122 template <typename T, size_t N>
 123 inline std::array<T, N>
 124 swap_byte(std::array<T, N> a)
 125 {
 126     for (T &v: a)
 127         v = swap_byte(v);
 128     return a;
 129 }
 130
 131 //The conversion functions with fixed endianness on both ends don't need to
 132 //be in a namespace
 133 template <typename T> inline T betole(T value) {return swap_byte(value);}
 134 template <typename T> inline T letobe(T value) {return swap_byte(value);}
 135
 136 //For conversions not involving the guest system, we can define the functions
 137 //conditionally based on the BYTE_ORDER macro and outside of the namespaces
 138 #if (defined(_BIG_ENDIAN) || !defined(_LITTLE_ENDIAN)) && BYTE_ORDER == BIG_ENDIAN
 139 const ByteOrder HostByteOrder = BigEndianByteOrder;
 140 template <typename T> inline T htole(T value) {return swap_byte(value);}
 141 template <typename T> inline T letoh(T value) {return swap_byte(value);}
 142 template <typename T> inline T htobe(T value) {return value;}
 143 template <typename T> inline T betoh(T value) {return value;}
 144 #elif defined(_LITTLE_ENDIAN) || BYTE_ORDER == LITTLE_ENDIAN
 145 const ByteOrder HostByteOrder = LittleEndianByteOrder;
 146 template <typename T> inline T htole(T value) {return value;}
 147 template <typename T> inline T letoh(T value) {return value;}
 148 template <typename T> inline T htobe(T value) {return swap_byte(value);}
 149 template <typename T> inline T betoh(T value) {return swap_byte(value);}
 150 #else
 151         #error Invalid Endianess
 152 #endif
 153
 154 template <typename T>
 155 inline T htog(T value, ByteOrder guest_byte_order)
 156 {
 157     return guest_byte_order == BigEndianByteOrder ?
 158         htobe(value) : htole(value);
 159 }
 160
 161 template <typename T>
 162 inline T gtoh(T value, ByteOrder guest_byte_order)
 163 {
 164     return guest_byte_order == BigEndianByteOrder ?
 165         betoh(value) : letoh(value);
 166 }
 167
 168 #endif // __SIM_BYTE_SWAP_HH__