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   1 /*
   2  * unaligned.h
   3  *
   4  * Inline functions for unaligned memory accesses.
   5  *
   6  * The author dedicates this file to the public domain.
   7  * You can do whatever you want with this file.
   8  */
   9
  10 #ifndef _WIMLIB_UNALIGNED_H
  11 #define _WIMLIB_UNALIGNED_H
  12
  13 #include "wimlib/compiler.h"
  14 #include "wimlib/endianness.h"
  15 #include "wimlib/types.h"
  16
  17 #define DEFINE_UNALIGNED_TYPE(type)                             \
  18 struct type##_unaligned {                                       \
  19         type v;                                                 \
  20 } _packed_attribute;                                            \
  21                                                                 \
  22 static inline type                                              \
  23 load_##type##_unaligned(const void *p)                          \
  24 {                                                               \
  25         return ((const struct type##_unaligned *)p)->v;         \
  26 }                                                               \
  27                                                                 \
  28 static inline void                                              \
  29 store_##type##_unaligned(type val, void *p)                     \
  30 {                                                               \
  31         ((struct type##_unaligned *)p)->v = val;                \
  32 }
  33
  34 DEFINE_UNALIGNED_TYPE(u16);
  35 DEFINE_UNALIGNED_TYPE(u32);
  36 DEFINE_UNALIGNED_TYPE(u64);
  37 DEFINE_UNALIGNED_TYPE(le16);
  38 DEFINE_UNALIGNED_TYPE(le32);
  39 DEFINE_UNALIGNED_TYPE(le64);
  40 DEFINE_UNALIGNED_TYPE(be16);
  41 DEFINE_UNALIGNED_TYPE(be32);
  42 DEFINE_UNALIGNED_TYPE(be64);
  43 DEFINE_UNALIGNED_TYPE(size_t);
  44 DEFINE_UNALIGNED_TYPE(machine_word_t);
  45
  46 #define load_word_unaligned     load_machine_word_t_unaligned
  47 #define store_word_unaligned    store_machine_word_t_unaligned
  48
  49 static inline u16
  50 get_unaligned_u16_le(const void *p)
  51 {
  52         u16 v;
  53
  54         if (UNALIGNED_ACCESS_IS_FAST) {
  55                 v = le16_to_cpu(load_le16_unaligned(p));
  56         } else {
  57                 const u8 *p8 = p;
  58                 v = 0;
  59                 v |= (u16)p8[0] << 0;
  60                 v |= (u16)p8[1] << 8;
  61         }
  62         return v;
  63 }
  64
  65 static inline u32
  66 get_unaligned_u32_le(const void *p)
  67 {
  68         u32 v;
  69
  70         if (UNALIGNED_ACCESS_IS_FAST) {
  71                 v = le32_to_cpu(load_le32_unaligned(p));
  72         } else {
  73                 const u8 *p8 = p;
  74                 v = 0;
  75                 v |= (u32)p8[0] << 0;
  76                 v |= (u32)p8[1] << 8;
  77                 v |= (u32)p8[2] << 16;
  78                 v |= (u32)p8[3] << 24;
  79         }
  80         return v;
  81 }
  82
  83 static inline void
  84 put_unaligned_u16_le(u16 v, void *p)
  85 {
  86         if (UNALIGNED_ACCESS_IS_FAST) {
  87                 store_le16_unaligned(cpu_to_le16(v), p);
  88         } else {
  89                 u8 *p8 = p;
  90                 p8[0] = (v >> 0) & 0xFF;
  91                 p8[1] = (v >> 8) & 0xFF;
  92         }
  93 }
  94
  95 static inline void
  96 put_unaligned_u32_le(u32 v, void *p)
  97 {
  98         if (UNALIGNED_ACCESS_IS_FAST) {
  99                 store_le32_unaligned(cpu_to_le32(v), p);
 100         } else {
 101                 u8 *p8 = p;
 102                 p8[0] = (v >> 0) & 0xFF;
 103                 p8[1] = (v >> 8) & 0xFF;
 104                 p8[2] = (v >> 16) & 0xFF;
 105                 p8[3] = (v >> 24) & 0xFF;
 106         }
 107 }
 108
 109 #endif /* _WIMLIB_UNALIGNED_H */