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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 void
  50 copy_word_unaligned(const void *src, void *dst)
  51 {
  52         store_word_unaligned(load_word_unaligned(src), dst);
  53 }
  54
  55 static inline machine_word_t
  56 repeat_byte(u8 b)
  57 {
  58         machine_word_t v;
  59
  60         BUILD_BUG_ON(WORDSIZE != 4 && WORDSIZE != 8);
  61
  62         v = b;
  63         v |= v << 8;
  64         v |= v << 16;
  65         v |= v << ((WORDSIZE == 8) ? 32 : 0);
  66         return v;
  67 }
  68
  69 static inline u16
  70 get_unaligned_u16_le(const void *p)
  71 {
  72         u16 v;
  73
  74         if (UNALIGNED_ACCESS_IS_FAST) {
  75                 v = le16_to_cpu(load_le16_unaligned(p));
  76         } else {
  77                 const u8 *p8 = p;
  78                 v = 0;
  79                 v |= (u16)p8[0] << 0;
  80                 v |= (u16)p8[1] << 8;
  81         }
  82         return v;
  83 }
  84
  85 static inline u32
  86 get_unaligned_u32_le(const void *p)
  87 {
  88         u32 v;
  89
  90         if (UNALIGNED_ACCESS_IS_FAST) {
  91                 v = le32_to_cpu(load_le32_unaligned(p));
  92         } else {
  93                 const u8 *p8 = p;
  94                 v = 0;
  95                 v |= (u32)p8[0] << 0;
  96                 v |= (u32)p8[1] << 8;
  97                 v |= (u32)p8[2] << 16;
  98                 v |= (u32)p8[3] << 24;
  99         }
 100         return v;
 101 }
 102
 103 static inline void
 104 put_unaligned_u16_le(u16 v, void *p)
 105 {
 106         if (UNALIGNED_ACCESS_IS_FAST) {
 107                 store_le16_unaligned(cpu_to_le16(v), p);
 108         } else {
 109                 u8 *p8 = p;
 110                 p8[0] = (v >> 0) & 0xFF;
 111                 p8[1] = (v >> 8) & 0xFF;
 112         }
 113 }
 114
 115 static inline void
 116 put_unaligned_u32_le(u32 v, void *p)
 117 {
 118         if (UNALIGNED_ACCESS_IS_FAST) {
 119                 store_le32_unaligned(cpu_to_le32(v), p);
 120         } else {
 121                 u8 *p8 = p;
 122                 p8[0] = (v >> 0) & 0xFF;
 123                 p8[1] = (v >> 8) & 0xFF;
 124                 p8[2] = (v >> 16) & 0xFF;
 125                 p8[3] = (v >> 24) & 0xFF;
 126         }
 127 }
 128
 129 #endif /* _WIMLIB_UNALIGNED_H */