/* Massimo: 
 *  This is a slightly modified version of the linux kernel file 
 *   /<source-dir>/include/asm-x86/atomic_32.h
 *
 */
#ifndef FF_ARCH_I386_ATOMIC_H
#define FF_ARCH_I386_ATOMIC_H

#if !defined(likely)
#define likely(x)	__builtin_expect(!!(x), 1)
#endif
#if !defined(unlikely)
#define unlikely(x)	__builtin_expect(!!(x), 0)
#endif

#define LOCK_PREFIX "lock ; "

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

/*
 * 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 unsigned long 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.
 */ 
#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.
 */ 
#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.
 */
static __inline__ void atomic_add(unsigned long i, atomic_t *v)
{
	__asm__ __volatile__(
		LOCK_PREFIX "addl %1,%0"
		:"+m" (v->counter)
		:"ir" (i));
}

/**
 * atomic_sub - subtract the atomic variable
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 * 
 * Atomically subtracts @i from @v.
 */
static __inline__ void atomic_sub(unsigned long i, atomic_t *v)
{
	__asm__ __volatile__(
		LOCK_PREFIX "subl %1,%0"
		:"+m" (v->counter)
		:"ir" (i));
}

/**
 * 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.
 */
static __inline__ unsigned long atomic_sub_and_test(unsigned long i, atomic_t *v)
{
	unsigned char c;

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

/**
 * atomic_inc - increment atomic variable
 * @v: pointer of type atomic_t
 * 
 * Atomically increments @v by 1.
 */ 
static __inline__ void atomic_inc(atomic_t *v)
{
	__asm__ __volatile__(
		LOCK_PREFIX "incl %0"
		:"+m" (v->counter));
}


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

/**
 * atomic_dec - decrement atomic variable
 * @v: pointer of type atomic_t
 * 
 * Atomically decrements @v by 1.
 */ 
static __inline__ void atomic_dec(atomic_t *v)
{
	__asm__ __volatile__(
		LOCK_PREFIX "decl %0"
		:"+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.
 */ 
static __inline__ unsigned long atomic_dec_and_test(atomic_t *v)
{
	unsigned char c;

	__asm__ __volatile__(
		LOCK_PREFIX "decl %0; sete %1"
		:"+m" (v->counter), "=qm" (c)
		: : "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.
 */ 
static __inline__ unsigned long atomic_inc_and_test(atomic_t *v)
{
	unsigned char c;

	__asm__ __volatile__(
		LOCK_PREFIX "incl %0; sete %1"
		:"+m" (v->counter), "=qm" (c)
		: : "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.
 */ 
static __inline__ unsigned long atomic_add_negative(unsigned long i, atomic_t *v)
{
	unsigned char c;

	__asm__ __volatile__(
		LOCK_PREFIX "addl %2,%0; sets %1"
		:"+m" (v->counter), "=qm" (c)
		:"ir" (i) : "memory");
	return c;
}

/**
 * atomic_add_return - add and return
 * @v: pointer of type atomic_t
 * @i: integer value to add
 *
 * Atomically adds @i to @v and returns @i + @v
 */
static __inline__ unsigned long atomic_add_return(unsigned long i, atomic_t *v)
{
	int __i;
#ifdef CONFIG_M386
	unsigned long flags;
	if(unlikely(boot_cpu_data.x86==3))
		goto no_xadd;
#endif
	/* Modern 486+ processor */
	__i = i;
	__asm__ __volatile__(
		LOCK_PREFIX "xaddl %0, %1;"
		:"=r"(i)
		:"m"(v->counter), "0"(i));
	return i + __i;

#ifdef CONFIG_M386
no_xadd: /* Legacy 386 processor */
	local_irq_save(flags);
	__i = atomic_read(v);
	atomic_set(v, i + __i);
	local_irq_restore(flags);
	return i + __i;
#endif
}

static __inline__ unsigned long atomic_sub_return(unsigned long i, atomic_t *v)
{
	return atomic_add_return(-i,v);
}


#define atomic_cmpxchg(v, old, New) (cmpxchg(&((v)->counter), (old), (New)))

struct __xchg_dummy {
	unsigned long a[100];
};
#define __xg(x) ((struct __xchg_dummy *)(x))

static __inline__ unsigned long cmpxchg(volatile void *ptr, unsigned long old,
					unsigned long New)
{
    unsigned long prev;
    asm volatile(LOCK_PREFIX "cmpxchgl %1,%2"
		 : "=a"(prev)
		 : "r"(New), "m"(*__xg(ptr)), "0"(old)
		 : "memory");
    return prev;
}

/**
 * atomic_add_unless - add unless the number is already a given value
 * @v: pointer of type atomic_t
 * @a: the amount to add to v...
 * @u: ...unless v is equal to u.
 *
 * Atomically adds @a to @v, so unsigned long as @v was not already @u.
 * Returns non-zero if @v was not @u, and zero otherwise.
 */
static inline unsigned long atomic_add_unless(atomic_t *v, unsigned long a, unsigned long u)
{
	unsigned long c, old;
	c = atomic_read(v);
	for (;;) {
		if (unlikely(c == (u)))
			break;
		old = atomic_cmpxchg((v), c, c + (a));
		if (likely(old == c))
			break;
		c = old;
	}
	return c != (u);
}

#endif /* FF_ARCH_I386_ATOMIC_H */
