bitops.h

来自「linux 内核源代码」· C头文件 代码 · 共 239 行

#ifndef _PARISC_BITOPS_H
#define _PARISC_BITOPS_H

#ifndef _LINUX_BITOPS_H
#error only <linux/bitops.h> can be included directly
#endif

#include <linux/compiler.h>
#include <asm/types.h>		/* for BITS_PER_LONG/SHIFT_PER_LONG */
#include <asm/byteorder.h>
#include <asm/atomic.h>

/*
 * HP-PARISC specific bit operations
 * for a detailed description of the functions please refer
 * to include/asm-i386/bitops.h or kerneldoc
 */

#define CHOP_SHIFTCOUNT(x) (((unsigned long) (x)) & (BITS_PER_LONG - 1))


#define smp_mb__before_clear_bit()      smp_mb()
#define smp_mb__after_clear_bit()       smp_mb()

/* See http://marc.theaimsgroup.com/?t=108826637900003 for discussion
 * on use of volatile and __*_bit() (set/clear/change):
 *	*_bit() want use of volatile.
 *	__*_bit() are "relaxed" and don't use spinlock or volatile.
 */

static __inline__ void set_bit(int nr, volatile unsigned long * addr)
{
	unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
	unsigned long flags;

	addr += (nr >> SHIFT_PER_LONG);
	_atomic_spin_lock_irqsave(addr, flags);
	*addr |= mask;
	_atomic_spin_unlock_irqrestore(addr, flags);
}

static __inline__ void clear_bit(int nr, volatile unsigned long * addr)
{
	unsigned long mask = ~(1UL << CHOP_SHIFTCOUNT(nr));
	unsigned long flags;

	addr += (nr >> SHIFT_PER_LONG);
	_atomic_spin_lock_irqsave(addr, flags);
	*addr &= mask;
	_atomic_spin_unlock_irqrestore(addr, flags);
}

static __inline__ void change_bit(int nr, volatile unsigned long * addr)
{
	unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
	unsigned long flags;

	addr += (nr >> SHIFT_PER_LONG);
	_atomic_spin_lock_irqsave(addr, flags);
	*addr ^= mask;
	_atomic_spin_unlock_irqrestore(addr, flags);
}

static __inline__ int test_and_set_bit(int nr, volatile unsigned long * addr)
{
	unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
	unsigned long old;
	unsigned long flags;
	int set;

	addr += (nr >> SHIFT_PER_LONG);
	_atomic_spin_lock_irqsave(addr, flags);
	old = *addr;
	set = (old & mask) ? 1 : 0;
	if (!set)
		*addr = old | mask;
	_atomic_spin_unlock_irqrestore(addr, flags);

	return set;
}

static __inline__ int test_and_clear_bit(int nr, volatile unsigned long * addr)
{
	unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
	unsigned long old;
	unsigned long flags;
	int set;

	addr += (nr >> SHIFT_PER_LONG);
	_atomic_spin_lock_irqsave(addr, flags);
	old = *addr;
	set = (old & mask) ? 1 : 0;
	if (set)
		*addr = old & ~mask;
	_atomic_spin_unlock_irqrestore(addr, flags);

	return set;
}

static __inline__ int test_and_change_bit(int nr, volatile unsigned long * addr)
{
	unsigned long mask = 1UL << CHOP_SHIFTCOUNT(nr);
	unsigned long oldbit;
	unsigned long flags;

	addr += (nr >> SHIFT_PER_LONG);
	_atomic_spin_lock_irqsave(addr, flags);
	oldbit = *addr;
	*addr = oldbit ^ mask;
	_atomic_spin_unlock_irqrestore(addr, flags);

	return (oldbit & mask) ? 1 : 0;
}

#include <asm-generic/bitops/non-atomic.h>

#ifdef __KERNEL__

/**
 * __ffs - find first bit in word. returns 0 to "BITS_PER_LONG-1".
 * @word: The word to search
 *
 * __ffs() return is undefined if no bit is set.
 *
 * 32-bit fast __ffs by LaMont Jones "lamont At hp com".
 * 64-bit enhancement by Grant Grundler "grundler At parisc-linux org".
 * (with help from willy/jejb to get the semantics right)
 *
 * This algorithm avoids branches by making use of nullification.
 * One side effect of "extr" instructions is it sets PSW[N] bit.
 * How PSW[N] (nullify next insn) gets set is determined by the 
 * "condition" field (eg "<>" or "TR" below) in the extr* insn.
 * Only the 1st and one of either the 2cd or 3rd insn will get executed.
 * Each set of 3 insn will get executed in 2 cycles on PA8x00 vs 16 or so
 * cycles for each mispredicted branch.
 */

static __inline__ unsigned long __ffs(unsigned long x)
{
	unsigned long ret;

	__asm__(
#ifdef CONFIG_64BIT
		" ldi       63,%1\n"
		" extrd,u,*<>  %0,63,32,%%r0\n"
		" extrd,u,*TR  %0,31,32,%0\n"	/* move top 32-bits down */
		" addi    -32,%1,%1\n"
#else
		" ldi       31,%1\n"
#endif
		" extru,<>  %0,31,16,%%r0\n"
		" extru,TR  %0,15,16,%0\n"	/* xxxx0000 -> 0000xxxx */
		" addi    -16,%1,%1\n"
		" extru,<>  %0,31,8,%%r0\n"
		" extru,TR  %0,23,8,%0\n"	/* 0000xx00 -> 000000xx */
		" addi    -8,%1,%1\n"
		" extru,<>  %0,31,4,%%r0\n"
		" extru,TR  %0,27,4,%0\n"	/* 000000x0 -> 0000000x */
		" addi    -4,%1,%1\n"
		" extru,<>  %0,31,2,%%r0\n"
		" extru,TR  %0,29,2,%0\n"	/* 0000000y, 1100b -> 0011b */
		" addi    -2,%1,%1\n"
		" extru,=  %0,31,1,%%r0\n"	/* check last bit */
		" addi    -1,%1,%1\n"
			: "+r" (x), "=r" (ret) );
	return ret;
}

#include <asm-generic/bitops/ffz.h>

/*
 * ffs: find first bit set. returns 1 to BITS_PER_LONG or 0 (if none 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).
 */
static __inline__ int ffs(int x)
{
	return x ? (__ffs((unsigned long)x) + 1) : 0;
}

/*
 * fls: find last (most significant) bit set.
 * fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
 */

static __inline__ int fls(int x)
{
	int ret;
	if (!x)
		return 0;

	__asm__(
	"	ldi		1,%1\n"
	"	extru,<>	%0,15,16,%%r0\n"
	"	zdep,TR		%0,15,16,%0\n"		/* xxxx0000 */
	"	addi		16,%1,%1\n"
	"	extru,<>	%0,7,8,%%r0\n"
	"	zdep,TR		%0,23,24,%0\n"		/* xx000000 */
	"	addi		8,%1,%1\n"
	"	extru,<>	%0,3,4,%%r0\n"
	"	zdep,TR		%0,27,28,%0\n"		/* x0000000 */
	"	addi		4,%1,%1\n"
	"	extru,<>	%0,1,2,%%r0\n"
	"	zdep,TR		%0,29,30,%0\n"		/* y0000000 (y&3 = 0) */
	"	addi		2,%1,%1\n"
	"	extru,=		%0,0,1,%%r0\n"
	"	addi		1,%1,%1\n"		/* if y & 8, add 1 */
		: "+r" (x), "=r" (ret) );

	return ret;
}

#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/hweight.h>
#include <asm-generic/bitops/lock.h>
#include <asm-generic/bitops/sched.h>

#endif /* __KERNEL__ */

#include <asm-generic/bitops/find.h>

#ifdef __KERNEL__

#include <asm-generic/bitops/ext2-non-atomic.h>

/* '3' is bits per byte */
#define LE_BYTE_ADDR ((sizeof(unsigned long) - 1) << 3)

#define ext2_set_bit_atomic(l,nr,addr) \
		test_and_set_bit((nr)   ^ LE_BYTE_ADDR, (unsigned long *)addr)
#define ext2_clear_bit_atomic(l,nr,addr) \
		test_and_clear_bit( (nr) ^ LE_BYTE_ADDR, (unsigned long *)addr)

#endif	/* __KERNEL__ */

#include <asm-generic/bitops/minix-le.h>

#endif /* _PARISC_BITOPS_H */