byteorder.h

   1 /*
   2  * Simple byteorder handling.
   3  *
   4  * Copyright (C) 1992-1995 Andrew Tridgell
   5  * Copyright (C) 2007-2020 Wayne Davison
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 3 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; if not, visit the http://fsf.org website.
  19  */
  20
  21 #undef CAREFUL_ALIGNMENT
  22
  23 /* We know that the x86 can handle misalignment and has the same
  24  * byte order (LSB-first) as the 32-bit numbers we transmit. */
  25 #if defined __i386__ || defined __i486__ || defined __i586__ || defined __i686__ || __amd64
  26 #define CAREFUL_ALIGNMENT 0
  27 #endif
  28
  29 #ifndef CAREFUL_ALIGNMENT
  30 #define CAREFUL_ALIGNMENT 1
  31 #endif
  32
  33 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
  34 #define UVAL(buf,pos) ((uint32)CVAL(buf,pos))
  35
  36 #if CAREFUL_ALIGNMENT
  37
  38 static inline uint32
  39 IVALu(const uchar *buf, int pos)
  40 {
  41         return UVAL(buf, pos)
  42              | UVAL(buf, pos + 1) << 8
  43              | UVAL(buf, pos + 2) << 16
  44              | UVAL(buf, pos + 3) << 24;
  45 }
  46
  47 static inline void
  48 SIVALu(uchar *buf, int pos, uint32 val)
  49 {
  50         CVAL(buf, pos)     = val;
  51         CVAL(buf, pos + 1) = val >> 8;
  52         CVAL(buf, pos + 2) = val >> 16;
  53         CVAL(buf, pos + 3) = val >> 24;
  54 }
  55
  56 static inline int64
  57 IVAL64(const char *buf, int pos)
  58 {
  59         return IVALu((uchar*)buf, pos) | (int64)IVALu((uchar*)buf, pos + 4) << 32;
  60 }
  61
  62 static inline void
  63 SIVAL64(char *buf, int pos, int64 val)
  64 {
  65         SIVALu((uchar*)buf, pos, val);
  66         SIVALu((uchar*)buf, pos + 4, val >> 32);
  67 }
  68
  69 #else /* !CAREFUL_ALIGNMENT */
  70
  71 /* This handles things for architectures like the 386 that can handle alignment errors.
  72  * WARNING: This section is dependent on the length of an int32 (and thus a uint32)
  73  * being correct (4 bytes)!  Set CAREFUL_ALIGNMENT if it is not. */
  74
  75 static inline uint32
  76 IVALu(const uchar *buf, int pos)
  77 {
  78         union {
  79                 const uchar *b;
  80                 const uint32 *num;
  81         } u;
  82         u.b = buf + pos;
  83         return *u.num;
  84 }
  85
  86 static inline void
  87 SIVALu(uchar *buf, int pos, uint32 val)
  88 {
  89         union {
  90                 uchar *b;
  91                 uint32 *num;
  92         } u;
  93         u.b = buf + pos;
  94         *u.num = val;
  95 }
  96
  97 static inline int64
  98 IVAL64(const char *buf, int pos)
  99 {
 100         union {
 101                 const char *b;
 102                 const int64 *num;
 103         } u;
 104         u.b = buf + pos;
 105         return *u.num;
 106 }
 107
 108 static inline void
 109 SIVAL64(char *buf, int pos, int64 val)
 110 {
 111         union {
 112                 char *b;
 113                 int64 *num;
 114         } u;
 115         u.b = buf + pos;
 116         *u.num = val;
 117 }
 118
 119 #endif /* !CAREFUL_ALIGNMENT */
 120
 121 static inline uint32
 122 IVAL(const char *buf, int pos)
 123 {
 124         return IVALu((uchar*)buf, pos);
 125 }
 126
 127 static inline void
 128 SIVAL(char *buf, int pos, uint32 val)
 129 {
 130         SIVALu((uchar*)buf, pos, val);
 131 }
 132