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#ifndef _I386_BITOPS_H
#define _I386_BITOPS_H
/*
* Copyright 1992, Linus Torvalds.
*/
/*
* These have to be done with inline assembly: that way the bit-setting
* is guaranteed to be atomic. All bit operations return 0 if the bit
* was cleared before the operation and != 0 if it was not.
*
* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
*/
#ifdef __SMP__
#define LOCK_PREFIX "lock ; "
#define SMPVOL volatile
#else
#define LOCK_PREFIX ""
#define SMPVOL
#endif
/*
* Some hacks to defeat gcc over-optimizations..
*/
struct __dummy { unsigned long a[100]; };
#define ADDR (*(struct __dummy *) addr)
#define CONST_ADDR (*(const struct __dummy *) addr)
extern __inline__ int set_bit(int nr, SMPVOL void * addr)
{
int oldbit;
__asm__ __volatile__(LOCK_PREFIX
"btsl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"ir" (nr));
return oldbit;
}
extern __inline__ int clear_bit(int nr, SMPVOL void * addr)
{
int oldbit;
__asm__ __volatile__(LOCK_PREFIX
"btrl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"ir" (nr));
return oldbit;
}
extern __inline__ int change_bit(int nr, SMPVOL void * addr)
{
int oldbit;
__asm__ __volatile__(LOCK_PREFIX
"btcl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"ir" (nr));
return oldbit;
}
/*
* This routine doesn't need to be atomic.
*/
extern __inline__ int test_bit(int nr, const SMPVOL void * addr)
{
return ((1UL << (nr & 31)) & (((const unsigned int *) addr)[nr >> 5])) != 0;
}
/*
* Find-bit routines..
*/
extern __inline__ int find_first_zero_bit(void * addr, unsigned size)
{
int res;
if (!size)
return 0;
__asm__("cld\n\t"
"movl $-1,%%eax\n\t"
"xorl %%edx,%%edx\n\t"
"repe; scasl\n\t"
"je 1f\n\t"
"xorl -4(%%edi),%%eax\n\t"
"subl $4,%%edi\n\t"
"bsfl %%eax,%%edx\n"
"1:\tsubl %%ebx,%%edi\n\t"
"shll $3,%%edi\n\t"
"addl %%edi,%%edx"
:"=d" (res)
:"c" ((size + 31) >> 5), "D" (addr), "b" (addr)
:"ax", "cx", "di");
return res;
}
extern __inline__ int find_next_zero_bit (void * addr, int size, int offset)
{
unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
int set = 0, bit = offset & 31, res;
if (bit) {
/*
* Look for zero in first byte
*/
__asm__("bsfl %1,%0\n\t"
"jne 1f\n\t"
"movl $32, %0\n"
"1:"
: "=r" (set)
: "r" (~(*p >> bit)));
if (set < (32 - bit))
return set + offset;
set = 32 - bit;
p++;
}
/*
* No zero yet, search remaining full bytes for a zero
*/
res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
return (offset + set + res);
}
/*
* ffz = Find First Zero in word. Undefined if no zero exists,
* so code should check against ~0UL first..
*/
extern __inline__ unsigned long ffz(unsigned long word)
{
__asm__("bsfl %1,%0"
:"=r" (word)
:"r" (~word));
return word;
}
#endif /* _I386_BITOPS_H */
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