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/*

 * Atomic operations that C can't guarantee us.  Useful for

 * resource counting etc..

 *

 * But use these as seldom as possible since they are much more slower

 * than regular operations.

 *

 * 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) 1996, 1997, 1999, 2000 by Ralf Baechle

 */

#ifndef _ASM_ATOMIC_H

#define _ASM_ATOMIC_H

#include <asm/sgidefs.h>

typedef struct { volatile int counter; } atomic_t;

#ifdef __KERNEL__

#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))

static __inline__ void atomic_add(int i, volatile atomic_t * v)

{

        unsigned long temp;

        __asm__ __volatile__(

                "1:\tll\t%0,%1\t\t\t# atomic_add\n\t"

                "addu\t%0,%2\n\t"

                "sc\t%0,%1\n\t"

                "beqz\t%0,1b"

                : "=&r" (temp), "=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, volatile atomic_t * v)

{

        unsigned long temp;

        __asm__ __volatile__(

                "1:\tll\t%0,%1\t\t\t# atomic_sub\n\t"

                "subu\t%0,%2\n\t"

                "sc\t%0,%1\n\t"

                "beqz\t%0,1b"

                : "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter));

}

/*

 * Same as above, but return the result value

 */

static __inline__ int atomic_add_return(int i, atomic_t * v)

{

        unsigned long temp, result;

        __asm__ __volatile__(

                ".set\tnoreorder\t\t\t# atomic_add_return\n"

                "1:\tll\t%1,%2\n\t"

                "addu\t%0,%1,%3\n\t"

                "sc\t%0,%2\n\t"

                "beqz\t%0,1b\n\t"

                "addu\t%0,%1,%3\n\t"

                "sync\n\t"

                ".set\treorder"

                : "=&r" (result), "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter)

                : "memory");

        return result;

}

static __inline__ int atomic_sub_return(int i, atomic_t * v)

{

        unsigned long temp, result;

        __asm__ __volatile__(

                ".set\tnoreorder\t\t\t# atomic_sub_return\n"

                "1:\tll\t%1,%2\n\t"

                "subu\t%0,%1,%3\n\t"

                "sc\t%0,%2\n\t"

                "beqz\t%0,1b\n\t"

                "subu\t%0,%1,%3\n\t"

                "sync\n\t"

                ".set\treorder"

                : "=&r" (result), "=&r" (temp), "=m" (v->counter)

                : "Ir" (i), "m" (v->counter)

                : "memory");

        return result;

}

#define atomic_dec_return(v) atomic_sub_return(1,(v))

#define atomic_inc_return(v) atomic_add_return(1,(v))

/*

 * 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.

 */

#define atomic_sub_and_test(i,v) (atomic_sub_return((i), (v)) == 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.

 */

#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)

/*

 * atomic_dec_and_test - decrement by 1 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.

 */

#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)

/*

 * 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.

 */

#define atomic_inc(v) atomic_add(1,(v))

/*

 * atomic_dec - decrement and test

 * @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.

 */

#define atomic_dec(v) atomic_sub(1,(v))

/*

 * 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.

 */

#define atomic_add_negative(i,v) (atomic_add_return(i, (v)) < 0)

/* Atomic operations are already serializing */

#define smp_mb__before_atomic_dec()     smp_mb()

#define smp_mb__after_atomic_dec()      smp_mb()

#define smp_mb__before_atomic_inc()     smp_mb()

#define smp_mb__after_atomic_inc()      smp_mb()

#endif /* defined(__KERNEL__) */

#endif /* _ASM_ATOMIC_H */