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#ifndef _ASM_WORD_AT_A_TIME_H
#define _ASM_WORD_AT_A_TIME_H
/*
* This is largely generic for little-endian machines, but the
* optimal byte mask counting is probably going to be something
* that is architecture-specific. If you have a reliably fast
* bit count instruction, that might be better than the multiply
* and shift, for example.
*/
#ifdef CONFIG_64BIT
/*
* Jan Achrenius on G+: microoptimized version of
* the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
* that works for the bytemasks without having to
* mask them first.
*/
static inline long count_masked_bytes(unsigned long mask)
{
return mask*0x0001020304050608ul >> 56;
}
#else /* 32-bit case */
/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
static inline long count_masked_bytes(long mask)
{
/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
long a = (0x0ff0001+mask) >> 23;
/* Fix the 1 for 00 case */
return a & mask;
}
#endif
#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
/* Return the high bit set in the first byte that is a zero */
static inline unsigned long has_zero(unsigned long a)
{
return ((a - REPEAT_BYTE(0x01)) & ~a) & REPEAT_BYTE(0x80);
}
/*
* Load an unaligned word from kernel space.
*
* In the (very unlikely) case of the word being a page-crosser
* and the next page not being mapped, take the exception and
* return zeroes in the non-existing part.
*/
static inline unsigned long load_unaligned_zeropad(const void *addr)
{
unsigned long ret, dummy;
asm(
"1:\tmov %2,%0\n"
"2:\n"
".section .fixup,\"ax\"\n"
"3:\t"
"lea %2,%1\n\t"
"and %3,%1\n\t"
"mov (%1),%0\n\t"
"leal %2,%%ecx\n\t"
"andl %4,%%ecx\n\t"
"shll $3,%%ecx\n\t"
"shr %%cl,%0\n\t"
"jmp 2b\n"
".previous\n"
_ASM_EXTABLE(1b, 3b)
:"=&r" (ret),"=&c" (dummy)
:"m" (*(unsigned long *)addr),
"i" (-sizeof(unsigned long)),
"i" (sizeof(unsigned long)-1));
return ret;
}
#endif /* _ASM_WORD_AT_A_TIME_H */
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