byteorder.h

   1 /*
   2  * Simple byteorder handling.
   3  *
   4  * Copyright (C) 1992-1995 Andrew Tridgell
   5  * Copyright (C) 2007-2008 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 #ifdef __i386__
  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 SSVALX(buf,pos,val) (CVAL(buf,pos)=(val)&0xFF,CVAL(buf,pos+1)=(val)>>8)
  42 #define SIVALX(buf,pos,val) (SSVALX(buf,pos,val&0xFFFF),SSVALX(buf,pos+2,val>>16))
  43 #define SIVAL(buf,pos,val) SIVALX((buf),(pos),((uint32)(val)))
  44
  45 #define IVALu(buf,pos) IVAL(buf,pos)
  46 #define SIVALu(buf,pos,val) SIVAL(buf,pos,val)
  47
  48 #else /* !CAREFUL_ALIGNMENT */
  49
  50 /* This handles things for architectures like the 386 that can handle alignment errors.
  51  * WARNING: This section is dependent on the length of an int32 (and thus a uint32)
  52  * being correct (4 bytes)!  Set CAREFUL_ALIGNMENT if it is not. */
  53
  54 # ifdef AVOID_BYTEORDER_INLINE
  55
  56 #define IVAL(buf,pos) (*(uint32 *)((char *)(buf) + (pos)))
  57 #define SIVAL(buf,pos,val) IVAL(buf,pos)=((uint32)(val))
  58
  59 #define IVALu(buf,pos) IVAL(buf,pos)
  60 #define SIVALu(buf,pos,val) SIVAL(buf,pos,val)
  61
  62 # else /* !AVOID_BYTEORDER_INLINE */
  63
  64 static inline uint32
  65 IVALu(const uchar *buf, int pos)
  66 {
  67         union {
  68                 const uchar *b;
  69                 const uint32 *num;
  70         } u;
  71         u.b = buf + pos;
  72         return *u.num;
  73 }
  74
  75 static inline void
  76 SIVALu(uchar *buf, int pos, uint32 val)
  77 {
  78         union {
  79                 uchar *b;
  80                 uint32 *num;
  81         } u;
  82         u.b = buf + pos;
  83         *u.num = val;
  84 }
  85
  86 static inline uint32
  87 IVAL(const char *buf, int pos)
  88 {
  89         return IVALu((uchar*)buf, pos);
  90 }
  91
  92 static inline void
  93 SIVAL(char *buf, int pos, uint32 val)
  94 {
  95         SIVALu((uchar*)buf, pos, val);
  96 }
  97
  98 # endif /* !AVOID_BYTEORDER_INLINE */
  99
 100 #endif /* !CAREFUL_ALIGNMENT */