2005/5/9

     
 

core_atomicop_linux.h

artefaktur
// -*- mode:C++; tab-width:2; c-basic-offset:2; indent-tabs-mode:nil -*- 
//
// Copyright (C) 2000-2005 by Roger Rene Kommer / artefaktur, Kassel, Germany.
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public License (LGPL).
// 
// 
// This library 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 
// License ACDK-FreeLicense document enclosed in the distribution
// for more for more details.
// This file is part of the Artefaktur Component Development Kit:
//                         ACDK
// 
// Please refer to
// - http://www.acdk.de
// - http://www.artefaktur.com
// - http://acdk.sourceforge.net
// for more information.
// 
// $Header: /cvsroot/acdk/acdk/acdk_core/src/acdk/lang/sys/core_atomicop_linux.h,v 1.4 2005/02/05 10:45:00 kommer Exp $
#ifndef core_atomic_linux_h
#define core_atomic_linux_h

extern "C" {

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 */

#define LOCK "lock ; "

/*
 * Make sure gcc doesn't try to be clever and move things around
 * on us. We need to use _exactly_ the address the user gave us,
 * not some alias that contains the same information.
 */
typedef struct { volatile int counter; } atomic_t;

#define ATOMIC_INIT(i)  { (i) }

/**
 * atomic_read - read atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically reads the value of @v.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
#define atomic_read(v)          ((v)->counter)

/**
 * atomic_set - set atomic variable
 * @v: pointer of type atomic_t
 * @i: required value
 *
 * Atomically sets the value of @v to @i.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
#define atomic_set(v,i)         (((v)->counter) = (i))

 
/**
 * atomic_add - add integer to atomic variable
 * @i: integer value to add
 * @v: pointer of type atomic_t
 *
 * Atomically adds @i to @v.  Note that the guaranteed useful range
 * of an atomic_t is only 24 bits.
 */
static __inline__ void atomic_add(int i, atomic_t *v)
{
        __asm__ __volatile__(
                LOCK "addl %1,%0"
                :"=m" (v->counter)
                :"ir" (i), "m" (v->counter));
}

/**
 * atomic_sub - subtract the atomic variable
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 *
 * Atomically subtracts @i from @v.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static __inline__ void atomic_sub(int i, atomic_t *v)
{
        __asm__ __volatile__(
                LOCK "subl %1,%0"
                :"=m" (v->counter)
                :"ir" (i), "m" (v->counter));
}

/**
 * atomic_sub_and_test - subtract value from variable and test result
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 *
 * Atomically subtracts @i from @v and returns
 * true if the result is zero, or false for all
 * other cases.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */

static __inline__ int atomic_sub_and_test(int i, atomic_t *v)
{
        unsigned char c;

        __asm__ __volatile__(
                LOCK "subl %2,%0; sete %1"
                :"=m" (v->counter), "=qm" (c)
                :"ir" (i), "m" (v->counter) : "memory");
        return c;
}

/**
 * atomic_inc - increment atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically increments @v by 1.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static __inline__ void atomic_inc(atomic_t *v)
{
        __asm__ __volatile__(
                LOCK "incl %0"
                :"=m" (v->counter)
                :"m" (v->counter));
}

/**
 * atomic_dec - decrement atomic variable
 * @v: pointer of type atomic_t
 *
 * Atomically decrements @v by 1.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static __inline__ void atomic_dec(atomic_t *v)
{
        __asm__ __volatile__(
                LOCK "decl %0"
                :"=m" (v->counter)
                :"m" (v->counter));
}

/**
 * atomic_dec_and_test - decrement and test
 * @v: pointer of type atomic_t
 *
 * Atomically decrements @v by 1 and
 * returns true if the result is 0, or false for all other
 * cases.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static __inline__ int atomic_dec_and_test(atomic_t *v)
{
        unsigned char c;

        __asm__ __volatile__(
                LOCK "decl %0; sete %1"
                :"=m" (v->counter), "=qm" (c)
                :"m" (v->counter) : "memory");
        return c != 0;
}

/**
 * atomic_inc_and_test - increment and test
 * @v: pointer of type atomic_t
 *
 * Atomically increments @v by 1
 * and returns true if the result is zero, or false for all
 * other cases.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static __inline__ int atomic_inc_and_test(atomic_t *v)
{
        unsigned char c;

        __asm__ __volatile__(
                LOCK "incl %0; sete %1"
                :"=m" (v->counter), "=qm" (c)
                :"m" (v->counter) : "memory");
        return c != 0;
}

/**
 * atomic_add_negative - add and test if negative
 * @v: pointer of type atomic_t
 * @i: integer value to add
 *
 * Atomically adds @i to @v and returns true
 * if the result is negative, or false when
 * result is greater than or equal to zero.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static __inline__ int atomic_add_negative(int i, atomic_t *v)
{
        unsigned char c;

        __asm__ __volatile__(                
	       LOCK "decl %0; sete %1"
                :"=m" (v->counter), "=qm" (c)
                :"m" (v->counter) : "memory");
        return c != 0;
}


/* These are x86-specific, used by some header files */
#define atomic_clear_mask(mask, addr) \
__asm__ __volatile__(LOCK "andl %0,%1" \
: : "r" (~(mask)),"m" (*addr) : "memory")

#define atomic_set_mask(mask, addr) \
__asm__ __volatile__(LOCK "orl %0,%1" \
: : "r" (mask),"m" (*addr) : "memory")

/* Atomic operations are already serializing on x86 */
#define smp_mb__before_atomic_dec()     barrier()
#define smp_mb__after_atomic_dec()      barrier()
#define smp_mb__before_atomic_inc()     barrier()
#define smp_mb__after_atomic_inc()      barrier()

} //extern C

#endif // core_atomic_linux_h