lib/unaligned.h

   1 /*
   2  *      Unaligned Data Accesses -- Generic Version, Network Order
   3  *
   4  *      (c) 2000 Martin Mares <mj@ucw.cz>
   5  *
   6  *      Can be freely distributed and used under the terms of the GNU GPL.
   7  */
   8
   9 #ifndef _BIRD_UNALIGNED_H_
  10 #define _BIRD_UNALIGNED_H_
  11
  12 /*
  13  *  We don't do any clever tricks with unaligned accesses since it's
  14  *  virtually impossible to figure out what alignment does the CPU want
  15  *  (unaligned accesses can be emulated by the OS which makes them work,
  16  *  but unusably slow). We use memcpy and hope GCC will optimize it out
  17  *  if possible.
  18  */
  19
  20 #include "lib/string.h"
  21
  22 static inline u16
  23 get_u16(const void *p)
  24 {
  25   u16 x;
  26   memcpy(&x, p, 2);
  27   return ntohs(x);
  28 }
  29
  30 static inline u32
  31 get_u32(const void *p)
  32 {
  33   u32 x;
  34   memcpy(&x, p, 4);
  35   return ntohl(x);
  36 }
  37
  38 static inline u64
  39 get_u64(const void *p)
  40 {
  41   u32 xh, xl;
  42   memcpy(&xh, p, 4);
  43   memcpy(&xl, p+4, 4);
  44   return (((u64) ntohl(xh)) << 32) | ntohl(xl);
  45 }
  46
  47 static inline void
  48 put_u8(void *p, u8 x)
  49 {
  50   memcpy(p, &x, 1);
  51 }
  52
  53 static inline void
  54 put_u16(void *p, u16 x)
  55 {
  56   x = htons(x);
  57   memcpy(p, &x, 2);
  58 }
  59
  60 static inline void
  61 put_u32(void *p, u32 x)
  62 {
  63   x = htonl(x);
  64   memcpy(p, &x, 4);
  65 }
  66
  67 static inline void
  68 put_u64(void *p, u64 x)
  69 {
  70   u32 xh, xl;
  71   xh = htonl(x >> 32);
  72   xl = htonl((u32) x);
  73   memcpy(p, &xh, 4);
  74   memcpy(p+4, &xl, 4);
  75 }
  76
  77 #endif