byteorder.h

   1 /*
   2  * Simple byteorder handling.
   3  *
   4  * Copyright (C) 1992-1995 Andrew Tridgell
   5  * Copyright (C) 2007-2019 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 #undef AVOID_BYTEORDER_INLINE
  23
  24 /* We know that the x86 can handle misalignment and has the same
  25  * byte order (LSB-first) as the 32-bit numbers we transmit. */
  26 #if defined __i386__ || defined __i486__ || defined __i586__ || defined __i686__ || __amd64
  27 #define CAREFUL_ALIGNMENT 0
  28 #endif
  29
  30 #ifndef CAREFUL_ALIGNMENT
  31 #define CAREFUL_ALIGNMENT 1
  32 #endif
  33
  34 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
  35 #define UVAL(buf,pos) ((uint32)CVAL(buf,pos))
  36
  37 #if CAREFUL_ALIGNMENT
  38
  39 #define PVAL(buf,pos) (UVAL(buf,pos)|UVAL(buf,(pos)+1)<<8)
  40 #define IVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+2)<<16)
  41 #define IVAL64(buf,pos) (IVAL(buf,pos)|(int64)IVAL(buf,(pos)+4)<<32)
  42 #define SSVALX(buf,pos,val) (CVAL(buf,pos)=(val)&0xFF,CVAL(buf,pos+1)=(val)>>8)
  43 #define SIVALX(buf,pos,val) (SSVALX(buf,pos,val&0xFFFF),SSVALX(buf,pos+2,val>>16))
  44 #define SIVAL(buf,pos,val) SIVALX(buf,pos,(uint32)(val))
  45 #define SIVAL64(buf,pos,val) (SIVAL(buf,pos,val),SIVAL(buf,(pos)+4,(val)>>32))
  46
  47 #define IVALu(buf,pos) IVAL(buf,pos)
  48 #define SIVALu(buf,pos,val) SIVAL(buf,pos,val)
  49
  50 #else /* !CAREFUL_ALIGNMENT */
  51
  52 /* This handles things for architectures like the 386 that can handle alignment errors.
  53  * WARNING: This section is dependent on the length of an int32 (and thus a uint32)
  54  * being correct (4 bytes)!  Set CAREFUL_ALIGNMENT if it is not. */
  55
  56 # ifdef AVOID_BYTEORDER_INLINE
  57
  58 #define IVAL(buf,pos) (*(uint32 *)((char *)(buf) + (pos)))
  59 #define SIVAL(buf,pos,val) IVAL(buf,pos)=((uint32)(val))
  60
  61 #define IVALu(buf,pos) IVAL(buf,pos)
  62 #define SIVALu(buf,pos,val) SIVAL(buf,pos,val)
  63
  64 # else /* !AVOID_BYTEORDER_INLINE */
  65
  66 static inline uint32
  67 IVALu(const uchar *buf, int pos)
  68 {
  69         union {
  70                 const uchar *b;
  71                 const uint32 *num;
  72         } u;
  73         u.b = buf + pos;
  74         return *u.num;
  75 }
  76
  77 static inline void
  78 SIVALu(uchar *buf, int pos, uint32 val)
  79 {
  80         union {
  81                 uchar *b;
  82                 uint32 *num;
  83         } u;
  84         u.b = buf + pos;
  85         *u.num = val;
  86 }
  87
  88 static inline uint32
  89 IVAL(const char *buf, int pos)
  90 {
  91         return IVALu((uchar*)buf, pos);
  92 }
  93
  94 static inline void
  95 SIVAL(char *buf, int pos, uint32 val)
  96 {
  97         SIVALu((uchar*)buf, pos, val);
  98 }
  99
 100 static inline int64
 101 IVAL64(const char *buf, int pos)
 102 {
 103         union {
 104                 const char *b;
 105                 const int64 *num;
 106         } u;
 107         u.b = buf + pos;
 108         return *u.num;
 109 }
 110
 111 static inline void
 112 SIVAL64(char *buf, int pos, int64 val)
 113 {
 114         union {
 115                 char *b;
 116                 int64 *num;
 117         } u;
 118         u.b = buf + pos;
 119         *u.num = val;
 120 }
 121
 122 # endif /* !AVOID_BYTEORDER_INLINE */
 123
 124 #endif /* !CAREFUL_ALIGNMENT */