graphene/LibOS/shim/include/bitop.h

/* Copyright (C) 2014 OSCAR lab, Stony Brook University
   This file is part of Graphene Library OS.

   Graphene Library OS is free software: you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   Graphene Library OS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/*
 * bitop.h
 */

#ifndef _BITOP_H
#define _BITOP_H

#define ADDR (*(volatile long *) addr)

#define LOCK_PREFIX ""

/**
 * set_bit - Atomically set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * This function is atomic and may not be reordered.  See __set_bit()
 * if you do not require the atomic guarantees.
 * Note that @nr may be almost arbitrarily large; this function is not
 * restricted to acting on a single-word quantity.
 */
static __inline__ void set_bit(int nr, volatile void * addr)
{
        __asm__ __volatile__( LOCK_PREFIX
                "btsl %1,%0"
                :"=m" (ADDR)
                :"dIr" (nr) : "memory");
}

/**
 * __set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * Unlike set_bit(), this function is non-atomic and may be reordered.
 * If it's called on the same region of memory simultaneously, the effect
 * may be that only one operation succeeds.
 */
static __inline__ void __set_bit(int nr, volatile void * addr)
{
        __asm__ volatile(
                "btsl %1,%0"
                :"=m" (ADDR)
                :"dIr" (nr) : "memory");
}

/**
 * clear_bit - Clears a bit in memory
 * @nr: Bit to clear
 * @addr: Address to start counting from
 *
 * clear_bit() is atomic and may not be reordered.  However, it does
 * not contain a memory barrier, so if it is used for locking purposes,
 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
 * in order to ensure changes are visible on other processors.
 */
static __inline__ void clear_bit(int nr, volatile void * addr)
{
        __asm__ __volatile__( LOCK_PREFIX
                "btrl %1,%0"
                :"=m" (ADDR)
                :"dIr" (nr));
}

static __inline__ void __clear_bit(int nr, volatile void * addr)
{
        __asm__ __volatile__(
                "btrl %1,%0"
                :"=m" (ADDR)
                :"dIr" (nr));
}

static __inline__ int constant_test_bit(int nr, const volatile void * addr)
{
        return ((1UL << (nr & 31)) & (((const volatile unsigned int *) addr)[nr >> 5])) != 0;
}

static __inline__ int variable_test_bit(int nr, volatile const void * addr)
{
        int oldbit;

        __asm__ __volatile__(
                "btl %2,%1\n\tsbbl %0,%0"
                :"=r" (oldbit)
                :"m" (ADDR),"dIr" (nr));
        return oldbit;
}

#define test_bit(nr,addr) \
(__builtin_constant_p(nr) ? \
 constant_test_bit((nr),(addr)) : \
 variable_test_bit((nr),(addr)))


#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

#endif