text: #ifndef __ASM_ARM_UNALIGNED_H
  #define __ASM_ARM_UNALIGNED_H
  
  #include <asm/types.h>
  
  extern int __bug_unaligned_x(void *ptr);
  
  /*
   * What is the most efficient way of loading/storing an unaligned value?
   *
   * That is the subject of this file.  Efficiency here is defined as
   * minimum code size with minimum register usage for the common cases.
   * It is currently not believed that long longs are common, so we
   * trade efficiency for the chars, shorts and longs against the long
   * longs.
   *
   * Current stats with gcc 2.7.2.2 for these functions:
   *
   *	ptrsize	get:	code	regs	put:	code	regs
   *	1		1	1		1	2
   *	2		3	2		3	2
   *	4		7	3		7	3
   *	8		20	6		16	6
   *
   * gcc 2.95.1 seems to code differently:
   *
   *	ptrsize	get:	code	regs	put:	code	regs
   *	1		1	1		1	2
   *	2		3	2		3	2
   *	4		7	4		7	4
   *	8		19	8		15	6
   *
   * which may or may not be more efficient (depending upon whether
   * you can afford the extra registers).  Hopefully the gcc 2.95
   * is inteligent enough to decide if it is better to use the
   * extra register, but evidence so far seems to suggest otherwise.
   *
   * Unfortunately, gcc is not able to optimise the high word
   * out of long long >> 32, or the low word from long long << 32
   */
  
  #define __get_unaligned_2(__p)					\
  	(__p[0] | __p[1] << 8)
  
  #define __get_unaligned_4(__p)					\
  	(__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
  
  #define get_unaligned(ptr)					\
  	({							\
  		__typeof__(*(ptr)) __v;				\
  		__u8 *__p = (__u8 *)(ptr);			\
  		switch (sizeof(*(ptr))) {			\
  		case 1:	__v = *(ptr);			break;	\
  		case 2: __v = __get_unaligned_2(__p);	break;	\
  		case 4: __v = __get_unaligned_4(__p);	break;	\
  		case 8: {					\
  				unsigned int __v1, __v2;	\
  				__v2 = __get_unaligned_4((__p+4)); \
  				__v1 = __get_unaligned_4(__p);	\
  				__v = ((unsigned long long)__v2 << 32 | __v1);	\
  			}					\
  			break;					\
  		default: __v = __bug_unaligned_x(__p);	break;	\
  		}						\
  		__v;						\
  	})
  
  
  static inline void __put_unaligned_2(__u32 __v, register __u8 *__p)
  {
  	*__p++ = __v;
  	*__p++ = __v >> 8;
  }
  
  static inline void __put_unaligned_4(__u32 __v, register __u8 *__p)
  {
  	__put_unaligned_2(__v >> 16, __p + 2);
  	__put_unaligned_2(__v, __p);
  }
  
  static inline void __put_unaligned_8(const unsigned long long __v, register __u8 *__p)
  {
  	/*
  	 * tradeoff: 8 bytes of stack for all unaligned puts (2
  	 * instructions), or an extra register in the long long
  	 * case - go for the extra register.
  	 */
  	__put_unaligned_4(__v >> 32, __p+4);
  	__put_unaligned_4(__v, __p);
  }
  
  /*
   * Try to store an unaligned value as efficiently as possible.
   */
  #define put_unaligned(val,ptr)					\
  	({							\
  		switch (sizeof(*(ptr))) {			\
  		case 1:						\
  			*(ptr) = (val);				\
  			break;					\
  		case 2: __put_unaligned_2((val),(__u8 *)(ptr));	\
  			break;					\
  		case 4:	__put_unaligned_4((val),(__u8 *)(ptr));	\
  			break;					\
  		case 8:	__put_unaligned_8((val),(__u8 *)(ptr)); \
  			break;					\
  		default: __bug_unaligned_x(ptr);		\
  			break;					\
  		}						\
  		(void) 0;					\
  	})
  
  
  #endif
  