LXR linux/include/asm-generic/unaligned.h

   1#ifndef _ASM_GENERIC_UNALIGNED_H_
   2#define _ASM_GENERIC_UNALIGNED_H_
   3
   4/*
   5 * For the benefit of those who are trying to port Linux to another
   6 * architecture, here are some C-language equivalents. 
   7 *
   8 * This is based almost entirely upon Richard Henderson's
   9 * asm-alpha/unaligned.h implementation.  Some comments were
  10 * taken from David Mosberger's asm-ia64/unaligned.h header.
  11 */
  12
  13#include <linux/types.h>
  14
  15/* 
  16 * The main single-value unaligned transfer routines.
  17 */
  18#define get_unaligned(ptr) \
  19        __get_unaligned((ptr), sizeof(*(ptr)))
  20#define put_unaligned(x,ptr) \
  21        ((void)sizeof(*(ptr)=(x)),\
  22        __put_unaligned((__force __u64)(x), (ptr), sizeof(*(ptr))))
  23
  24/*
  25 * This function doesn't actually exist.  The idea is that when
  26 * someone uses the macros below with an unsupported size (datatype),
  27 * the linker will alert us to the problem via an unresolved reference
  28 * error.
  29 */
  30extern void bad_unaligned_access_length(void) __attribute__((noreturn));
  31
  32struct __una_u64 { __u64 x __attribute__((packed)); };
  33struct __una_u32 { __u32 x __attribute__((packed)); };
  34struct __una_u16 { __u16 x __attribute__((packed)); };
  35
  36/*
  37 * Elemental unaligned loads 
  38 */
  39
  40static inline __u64 __uldq(const __u64 *addr)
  41{
  42        const struct __una_u64 *ptr = (const struct __una_u64 *) addr;
  43        return ptr->x;
  44}
  45
  46static inline __u32 __uldl(const __u32 *addr)
  47{
  48        const struct __una_u32 *ptr = (const struct __una_u32 *) addr;
  49        return ptr->x;
  50}
  51
  52static inline __u16 __uldw(const __u16 *addr)
  53{
  54        const struct __una_u16 *ptr = (const struct __una_u16 *) addr;
  55        return ptr->x;
  56}
  57
  58/*
  59 * Elemental unaligned stores 
  60 */
  61
  62static inline void __ustq(__u64 val, __u64 *addr)
  63{
  64        struct __una_u64 *ptr = (struct __una_u64 *) addr;
  65        ptr->x = val;
  66}
  67
  68static inline void __ustl(__u32 val, __u32 *addr)
  69{
  70        struct __una_u32 *ptr = (struct __una_u32 *) addr;
  71        ptr->x = val;
  72}
  73
  74static inline void __ustw(__u16 val, __u16 *addr)
  75{
  76        struct __una_u16 *ptr = (struct __una_u16 *) addr;
  77        ptr->x = val;
  78}
  79
  80#define __get_unaligned(ptr, size) ({           \
  81        const void *__gu_p = ptr;               \
  82        __u64 __val;                            \
  83        switch (size) {                         \
  84        case 1:                                 \
  85                __val = *(const __u8 *)__gu_p;  \
  86                break;                          \
  87        case 2:                                 \
  88                __val = __uldw(__gu_p);         \
  89                break;                          \
  90        case 4:                                 \
  91                __val = __uldl(__gu_p);         \
  92                break;                          \
  93        case 8:                                 \
  94                __val = __uldq(__gu_p);         \
  95                break;                          \
  96        default:                                \
  97                bad_unaligned_access_length();  \
  98        };                                      \
  99        (__force __typeof__(*(ptr)))__val;      \
 100})
 101
 102#define __put_unaligned(val, ptr, size)         \
 103({                                              \
 104        void *__gu_p = ptr;                     \
 105        switch (size) {                         \
 106        case 1:                                 \
 107                *(__u8 *)__gu_p = (__force __u8)val;            \
 108                break;                          \
 109        case 2:                                 \
 110                __ustw((__force __u16)val, __gu_p);             \
 111                break;                          \
 112        case 4:                                 \
 113                __ustl((__force __u32)val, __gu_p);             \
 114                break;                          \
 115        case 8:                                 \
 116                __ustq(val, __gu_p);            \
 117                break;                          \
 118        default:                                \
 119                bad_unaligned_access_length();  \
 120        };                                      \
 121        (void)0;                                \
 122})
 123
 124#endif /* _ASM_GENERIC_UNALIGNED_H */
 125