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 "sysdep/unix/endian.h"
  21 #include "lib/string.h"
  22
  23 static inline u8
  24 get_u8(const void *p)
  25 {
  26   return * (u8 *) p;
  27 }
  28
  29 static inline u16
  30 get_u16(const void *p)
  31 {
  32   u16 x;
  33   memcpy(&x, p, 2);
  34   return ntohs(x);
  35 }
  36
  37 static inline u32
  38 get_u24(const void *P)
  39 {
  40   const byte *p = P;
  41   return (p[0] << 16) + (p[1] << 8) + p[2];
  42 }
  43
  44 static inline u32
  45 get_u32(const void *p)
  46 {
  47   u32 x;
  48   memcpy(&x, p, 4);
  49   return ntohl(x);
  50 }
  51
  52 static inline u64
  53 get_u64(const void *p)
  54 {
  55   u32 xh, xl;
  56   memcpy(&xh, p, 4);
  57   memcpy(&xl, p+4, 4);
  58   return (((u64) ntohl(xh)) << 32) | ntohl(xl);
  59 }
  60
  61 static inline void
  62 put_u8(void *p, u8 x)
  63 {
  64   memcpy(p, &x, 1);
  65 }
  66
  67 static inline void
  68 put_u16(void *p, u16 x)
  69 {
  70   x = htons(x);
  71   memcpy(p, &x, 2);
  72 }
  73
  74 static inline void
  75 put_u24(void *p, u32 x)
  76 {
  77   x = htonl(x);
  78   memcpy(p, ((char *) &x) + 1, 3);
  79 }
  80
  81 static inline void
  82 put_u32(void *p, u32 x)
  83 {
  84   x = htonl(x);
  85   memcpy(p, &x, 4);
  86 }
  87
  88 static inline void
  89 put_u64(void *p, u64 x)
  90 {
  91   u32 xh, xl;
  92   xh = htonl(x >> 32);
  93   xl = htonl((u32) x);
  94   memcpy(p, &xh, 4);
  95   memcpy(p+4, &xl, 4);
  96 }
  97
  98 static inline void
  99 get_u32s(const void *p, u32 *x, int n)
 100 {
 101   int i;
 102   memcpy(x, p, 4*n);
 103   for (i = 0; i < n; i++)
 104     x[i] = ntohl(x[i]);
 105 }
 106
 107 static inline void
 108 put_u32s(void *p, const u32 *x, int n)
 109 {
 110   int i;
 111   for (i = 0; i < n; i++)
 112     put_u32((byte *) p + 4*i, x[i]);
 113 }
 114
 115
 116 #endif