linux/include/asm-xtensa/bitops.h

/*
 * include/asm-xtensa/bitops.h
 *
 * Atomic operations that C can't guarantee us.Useful for resource counting etc.
 *
 * 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) 2001 - 2005 Tensilica Inc.
 */

#ifndef _XTENSA_BITOPS_H
#define _XTENSA_BITOPS_H

#ifdef __KERNEL__

#include <asm/processor.h>
#include <asm/byteorder.h>
#include <asm/system.h>

#ifdef CONFIG_SMP
# error SMP not supported on this architecture
#endif

#define smp_mb__before_clear_bit()	barrier()
#define smp_mb__after_clear_bit()	barrier()

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

#if XCHAL_HAVE_NSA

static __inline__ int __cntlz (unsigned long x)
{
	int lz;
	asm ("nsau %0, %1" : "=r" (lz) : "r" (x));
	return 31 - lz;
}

#else

static __inline__ int __cntlz (unsigned long x)
{
	unsigned long sum, x1, x2, x4, x8, x16;
	x1  = x & 0xAAAAAAAA;
	x2  = x & 0xCCCCCCCC;
	x4  = x & 0xF0F0F0F0;
	x8  = x & 0xFF00FF00;
	x16 = x & 0xFFFF0000;
	sum = x2 ? 2 : 0;
	sum += (x16 != 0) * 16;
	sum += (x8 != 0) * 8;
	sum += (x4 != 0) * 4;
	sum += (x1 != 0);

	return sum;
}

#endif

/*
 * ffz: Find first zero in word. Undefined if no zero exists.
 * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
 */

static __inline__ int ffz(unsigned long x)
{
	if ((x = ~x) == 0)
		return 32;
	return __cntlz(x & -x);
}

/*
 * __ffs: Find first bit set in word. Return 0 for bit 0
 */

static __inline__ int __ffs(unsigned long x)
{
	return __cntlz(x & -x);
}

/*
 * ffs: Find first bit set in word. 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(unsigned long x)
{
	return __cntlz(x & -x) + 1;
}

/*
 * fls: Find last (most-significant) bit set in word.
 * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
 */

static __inline__ int fls (unsigned int x)
{
	return __cntlz(x);
}
#include <asm-generic/bitops/fls64.h>
#include <asm-generic/bitops/find.h>
#include <asm-generic/bitops/ext2-non-atomic.h>

#ifdef __XTENSA_EL__
# define ext2_set_bit_atomic(lock,nr,addr) test_and_set_bit((nr),(addr))
# define ext2_clear_bit_atomic(lock,nr,addr) test_and_clear_bit((nr),(addr))
#elif defined(__XTENSA_EB__)
# define ext2_set_bit_atomic(lock,nr,addr) test_and_set_bit((nr) ^ 0x18, (addr))
# define ext2_clear_bit_atomic(lock,nr,addr) test_and_clear_bit((nr)^0x18,(addr))
#else
# error processor byte order undefined!
#endif

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

#endif	/* __KERNEL__ */

#endif	/* _XTENSA_BITOPS_H */