bitops.h

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 1994, 95, 96, 97, 98, 99, 2000  Ralf Baechle
 * Copyright (c) 1999, 2000  Silicon Graphics, Inc.
 */
#ifndef _ASM_BITOPS_H
#define _ASM_BITOPS_H

#include <linux/types.h>
#include <linux/byteorder/swab.h>		/* sigh ... */

#ifndef __KERNEL__
#error "Don't do this, sucker ..."
#endif

#include <asm/system.h>
#include <asm/sgidefs.h>
#include <asm/mipsregs.h>

/*
 * clear_bit() doesn't provide any barrier for the compiler.
 */
#define smp_mb__before_clear_bit()	barrier()
#define smp_mb__after_clear_bit()	barrier()

/*
 * These functions for MIPS ISA > 1 are interrupt and SMP proof and
 * interrupt friendly
 */

extern __inline__ void
set_bit(unsigned long nr, volatile void *addr)
{
	unsigned long *m = ((unsigned long *) addr) + (nr >> 6);
	unsigned long temp;

	__asm__ __volatile__(
		"1:\tlld\t%0, %1\t\t# set_bit\n\t"
		"or\t%0, %2\n\t"
		"scd\t%0, %1\n\t"
		"beqz\t%0, 1b"
		: "=&r" (temp), "=m" (*m)
		: "ir" (1UL << (nr & 0x3f)), "m" (*m)
		: "memory");
}

/* WARNING: non atomic and it can be reordered! */
extern __inline__ void __set_bit(int nr, volatile void * addr)
{
	unsigned long * m = ((unsigned long *) addr) + (nr >> 6);

	*m |= 1UL << (nr & 0x3f);
}

extern __inline__ void
clear_bit(unsigned long nr, volatile void *addr)
{
	unsigned long *m = ((unsigned long *) addr) + (nr >> 6);
	unsigned long temp;

	__asm__ __volatile__(
		"1:\tlld\t%0, %1\t\t# clear_bit\n\t"
		"and\t%0, %2\n\t"
		"scd\t%0, %1\n\t"
		"beqz\t%0, 1b\n\t"
		: "=&r" (temp), "=m" (*m)
		: "ir" (~(1UL << (nr & 0x3f))), "m" (*m));
}


extern __inline__ void
change_bit(unsigned long nr, volatile void *addr)
{
	unsigned long *m = ((unsigned long *) addr) + (nr >> 6);
	unsigned long temp;

	__asm__ __volatile__(
		"1:\tlld\t%0, %1\t\t# change_bit\n\t"
		"xor\t%0, %2\n\t"
		"scd\t%0, %1\n\t"
		"beqz\t%0, 1b"
		:"=&r" (temp), "=m" (*m)
		:"ir" (1UL << (nr & 0x3f)), "m" (*m));
}

extern __inline__ unsigned long
test_and_set_bit(unsigned long nr, volatile void *addr)
{
	unsigned long *m = ((unsigned long *) addr) + (nr >> 6);
	unsigned long temp, res;

	__asm__ __volatile__(
		".set\tnoreorder\t\t# test_and_set_bit\n"
		"1:\tlld\t%0, %1\n\t"
		"or\t%2, %0, %3\n\t"
		"scd\t%2, %1\n\t"
		"beqz\t%2, 1b\n\t"
		" and\t%2, %0, %3\n\t"
		".set\treorder"
		: "=&r" (temp), "=m" (*m), "=&r" (res)
		: "r" (1UL << (nr & 0x3f)), "m" (*m)
		: "memory");

	return res != 0;
}

extern __inline__ int __test_and_set_bit(int nr, volatile void * addr)
{
	int mask, retval;
	volatile long *a = addr;

	a += nr >> 6;
	mask = 1 << (nr & 0x3f);
	retval = (mask & *a) != 0;
	*a |= mask;

	return retval;
}

extern __inline__ unsigned long
test_and_clear_bit(unsigned long nr, volatile void *addr)
{
	unsigned long *m = ((unsigned long *) addr) + (nr >> 6);
	unsigned long temp, res;

	__asm__ __volatile__(
		".set\tnoreorder\t\t# test_and_clear_bit\n"
		"1:\tlld\t%0, %1\n\t"
		"or\t%2, %0, %3\n\t"
		"xor\t%2, %3\n\t"
		"scd\t%2, %1\n\t"
		"beqz\t%2, 1b\n\t"
		" and\t%2, %0, %3\n\t"
		".set\treorder"
		: "=&r" (temp), "=m" (*m), "=&r" (res)
		: "r" (1UL << (nr & 0x3f)), "m" (*m)
		: "memory");

	return res != 0;
}

extern __inline__ int __test_and_clear_bit(int nr, volatile void * addr)
{
	int     mask, retval;
	volatile long    *a = addr;

	a += nr >> 6;
	mask = 1 << (nr & 0x3f);
	retval = (mask & *a) != 0;
	*a &= ~mask;

	return retval;
}

extern __inline__ unsigned long
test_and_change_bit(unsigned long nr, volatile void *addr)
{
	unsigned long *m = ((unsigned long *) addr) + (nr >> 6);
	unsigned long temp, res;

	__asm__ __volatile__(
		".set\tnoreorder\t\t# test_and_change_bit\n"
		"1:\tlld\t%0, %1\n\t"
		"xor\t%2, %0, %3\n\t"
		"scd\t%2, %1\n\t"
		"beqz\t%2, 1b\n\t"
		" and\t%2, %0, %3\n\t"
		".set\treorder"
		: "=&r" (temp), "=m" (*m), "=&r" (res)
		: "r" (1UL << (nr & 0x3f)), "m" (*m)
		: "memory");

	return res != 0;
}

extern __inline__ unsigned long
test_bit(int nr, volatile void * addr)
{
	return 1UL & (((const long *) addr)[nr >> 6] >> (nr & 0x3f));
}

#ifndef __MIPSEB__

/* Little endian versions. */

extern __inline__ int
find_first_zero_bit (void *addr, unsigned size)
{
	unsigned long dummy;
	int res;

	if (!size)
		return 0;

	__asm__ (".set\tnoreorder\n\t"
		".set\tnoat\n"
		"1:\tsubu\t$1,%6,%0\n\t"
		"blez\t$1,2f\n\t"
		"lw\t$1,(%5)\n\t"
		"addiu\t%5,4\n\t"
#if (_MIPS_ISA == _MIPS_ISA_MIPS2) || (_MIPS_ISA == _MIPS_ISA_MIPS3) || \
    (_MIPS_ISA == _MIPS_ISA_MIPS4) || (_MIPS_ISA == _MIPS_ISA_MIPS5)
		"beql\t%1,$1,1b\n\t"
		"addiu\t%0,32\n\t"
#else
		"addiu\t%0,32\n\t"
		"beq\t%1,$1,1b\n\t"
		"nop\n\t"
		"subu\t%0,32\n\t"
#endif
		"li\t%1,1\n"
		"1:\tand\t%2,$1,%1\n\t"
		"beqz\t%2,2f\n\t"
		"sll\t%1,%1,1\n\t"
		"bnez\t%1,1b\n\t"
		"add\t%0,%0,1\n\t"
		".set\tat\n\t"
		".set\treorder\n"
		"2:"
		: "=r" (res), "=r" (dummy), "=r" (addr)
		: "0" ((signed int) 0), "1" ((unsigned int) 0xffffffff),
		  "2" (addr), "r" (size)
		: "$1");

	return res;
}

extern __inline__ int
find_next_zero_bit (void * addr, int size, int offset)
{
	unsigned int *p = ((unsigned int *) addr) + (offset >> 5);
	int set = 0, bit = offset & 31, res;
	unsigned long dummy;

	if (bit) {
		/*
		 * Look for zero in first byte
		 */
		__asm__(".set\tnoreorder\n\t"
			".set\tnoat\n"
			"1:\tand\t$1,%4,%1\n\t"
			"beqz\t$1,1f\n\t"
			"sll\t%1,%1,1\n\t"
			"bnez\t%1,1b\n\t"
			"addiu\t%0,1\n\t"
			".set\tat\n\t"
			".set\treorder\n"
			"1:"
			: "=r" (set), "=r" (dummy)
			: "0" (0), "1" (1 << bit), "r" (*p)
			: "$1");
		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 int *) addr));
	return offset + set + res;
}

#endif /* !(__MIPSEB__) */

/*
 * 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)
{
	unsigned long k;

	word = ~word;
	k = 63;
	if (word & 0x00000000ffffffffUL) { k -= 32; word <<= 32; }
	if (word & 0x0000ffff00000000UL) { k -= 16; word <<= 16; }
	if (word & 0x00ff000000000000UL) { k -= 8;  word <<= 8;  }
	if (word & 0x0f00000000000000UL) { k -= 4;  word <<= 4;  }
	if (word & 0x3000000000000000UL) { k -= 2;  word <<= 2;  }
	if (word & 0x4000000000000000UL) { k -= 1; }

	return k;
}

#ifdef __KERNEL__

/*
 * ffs: find first bit set. This is defined the same way as
 * the libc and compiler builtin ffs routines, therefore
 * differs in spirit from the above ffz (man ffs).
 */

#define ffs(x) generic_ffs(x)

/*
 * hweightN: returns the hamming weight (i.e. the number
 * of bits set) of a N-bit word
 */

#define hweight32(x) generic_hweight32(x)
#define hweight16(x) generic_hweight16(x)
#define hweight8(x)  generic_hweight8(x)

#endif /* __KERNEL__ */

#ifdef __MIPSEB__

/*
 * find_next_zero_bit() finds the first zero bit in a bit string of length
 * 'size' bits, starting the search at bit 'offset'. This is largely based
 * on Linus's ALPHA routines, which are pretty portable BTW.
 */

extern __inline__ unsigned long
find_next_zero_bit(void *addr, unsigned long size, unsigned long offset)
{
	unsigned long *p = ((unsigned long *) addr) + (offset >> 6);
	unsigned long result = offset & ~63UL;
	unsigned long tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset &= 63UL;
	if (offset) {
		tmp = *(p++);
		tmp |= ~0UL >> (64-offset);
		if (size < 64)
			goto found_first;
		if (~tmp)
			goto found_middle;
		size -= 64;
		result += 64;
	}
	while (size & ~63UL) {
		if (~(tmp = *(p++)))
			goto found_middle;
		result += 64;
		size -= 64;
	}
	if (!size)
		return result;
	tmp = *p;

found_first:
	tmp |= ~0UL << size;
found_middle:
	return result + ffz(tmp);
}

#define find_first_zero_bit(addr, size) \
        find_next_zero_bit((addr), (size), 0)

#endif /* (__MIPSEB__) */

#ifdef __KERNEL__

/* Now for the ext2 filesystem bit operations and helper routines. */

#ifdef __MIPSEB__

extern inline int
ext2_set_bit(int nr,void * addr)
{
	int		mask, retval, flags;
	unsigned char	*ADDR = (unsigned char *) addr;

	ADDR += nr >> 3;
	mask = 1 << (nr & 0x07);
	save_and_cli(flags);
	retval = (mask & *ADDR) != 0;
	*ADDR |= mask;
	restore_flags(flags);
	return retval;
}

extern inline int
ext2_clear_bit(int nr, void * addr)
{
	int		mask, retval, flags;
	unsigned char	*ADDR = (unsigned char *) addr;

	ADDR += nr >> 3;
	mask = 1 << (nr & 0x07);
	save_and_cli(flags);
	retval = (mask & *ADDR) != 0;
	*ADDR &= ~mask;
	restore_flags(flags);
	return retval;
}

extern inline int
ext2_test_bit(int nr, const void * addr)
{
	int			mask;
	const unsigned char	*ADDR = (const unsigned char *) addr;

	ADDR += nr >> 3;
	mask = 1 << (nr & 0x07);
	return ((mask & *ADDR) != 0);
}

#define ext2_find_first_zero_bit(addr, size) \
        ext2_find_next_zero_bit((addr), (size), 0)

extern inline unsigned int
ext2_find_next_zero_bit(void *addr, unsigned long size, unsigned long offset)
{
	unsigned int *p = ((unsigned int *) addr) + (offset >> 5);
	unsigned int result = offset & ~31UL;
	unsigned int tmp;

	if (offset >= size)
		return size;
	size -= result;
	offset &= 31UL;
	if(offset) {
		/* We hold the little endian value in tmp, but then the
		 * shift is illegal. So we could keep a big endian value
		 * in tmp, like this:
		 *
		 * tmp = __swab32(*(p++));
		 * tmp |= ~0UL >> (32-offset);
		 *
		 * but this would decrease preformance, so we change the
		 * shift:
		 */
		tmp = *(p++);
		tmp |= __swab32(~0UL >> (32-offset));
		if(size < 32)
			goto found_first;
		if(~tmp)
			goto found_middle;
		size -= 32;
		result += 32;
	}
	while(size & ~31UL) {
		if(~(tmp = *(p++)))
			goto found_middle;
		result += 32;
		size -= 32;
	}
	if(!size)
		return result;
	tmp = *p;

found_first:
	/* tmp is little endian, so we would have to swab the shift,
	 * see above. But then we have to swab tmp below for ffz, so
	 * we might as well do this here.
	 */
	return result + ffz(__swab32(tmp) | (~0UL << size));
found_middle:
	return result + ffz(__swab32(tmp));
}
#else /* !(__MIPSEB__) */

/* Native ext2 byte ordering, just collapse using defines. */
#define ext2_set_bit(nr, addr) test_and_set_bit((nr), (addr))
#define ext2_clear_bit(nr, addr) test_and_clear_bit((nr), (addr))
#define ext2_test_bit(nr, addr) test_bit((nr), (addr))
#define ext2_find_first_zero_bit(addr, size) find_first_zero_bit((addr), (size))
#define ext2_find_next_zero_bit(addr, size, offset) \
                find_next_zero_bit((addr), (size), (offset))
 
#endif /* !(__MIPSEB__) */

/*
 * Bitmap functions for the minix filesystem.
 * FIXME: These assume that Minix uses the native byte/bitorder.
 * This limits the Minix filesystem's value for data exchange very much.
 */
#define minix_test_and_set_bit(nr,addr) test_and_set_bit(nr,addr)
#define minix_set_bit(nr,addr) set_bit(nr,addr)
#define minix_test_and_clear_bit(nr,addr) test_and_clear_bit(nr,addr)
#define minix_test_bit(nr,addr) test_bit(nr,addr)
#define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)

#endif /* __KERNEL__ */

#endif /* _ASM_BITOPS_H */