/*-
 * Copyright (c) 1998 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/i386/include/atomic.h,v 1.9.2.1 2000/07/07 00:38:47 obrien Exp $
 * $DragonFly: src/sys/i386/include/Attic/atomic.h,v 1.8 2004/07/29 20:31:13 dillon Exp $
 */
#ifndef _MACHINE_ATOMIC_H_
#define _MACHINE_ATOMIC_H_

/*
 * Various simple arithmetic on memory which is atomic in the presence
 * of interrupts and multiple processors.
 *
 * atomic_set_char(P, V)	(*(u_char*)(P) |= (V))
 * atomic_clear_char(P, V)	(*(u_char*)(P) &= ~(V))
 * atomic_add_char(P, V)	(*(u_char*)(P) += (V))
 * atomic_subtract_char(P, V)	(*(u_char*)(P) -= (V))
 *
 * atomic_set_short(P, V)	(*(u_short*)(P) |= (V))
 * atomic_clear_short(P, V)	(*(u_short*)(P) &= ~(V))
 * atomic_add_short(P, V)	(*(u_short*)(P) += (V))
 * atomic_subtract_short(P, V)	(*(u_short*)(P) -= (V))
 *
 * atomic_set_int(P, V)		(*(u_int*)(P) |= (V))
 * atomic_clear_int(P, V)	(*(u_int*)(P) &= ~(V))
 * atomic_add_int(P, V)		(*(u_int*)(P) += (V))
 * atomic_subtract_int(P, V)	(*(u_int*)(P) -= (V))
 *
 * atomic_set_long(P, V)	(*(u_long*)(P) |= (V))
 * atomic_clear_long(P, V)	(*(u_long*)(P) &= ~(V))
 * atomic_add_long(P, V)	(*(u_long*)(P) += (V))
 * atomic_subtract_long(P, V)	(*(u_long*)(P) -= (V))
 */

/*
 * The above functions are expanded inline in the statically-linked
 * kernel.  Lock prefixes are generated if an SMP kernel is being
 * built.
 *
 * Kernel modules call real functions which are built into the kernel.
 * This allows kernel modules to be portable between UP and SMP systems.
 */
#if defined(KLD_MODULE)
#define ATOMIC_ASM(NAME, TYPE, OP, V)			\
	extern void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v); \
	extern void atomic_##NAME##_##TYPE##_nonlocked(volatile u_##TYPE *p, u_##TYPE v);
#else /* !KLD_MODULE */
#if defined(SMP)
#define MPLOCKED	"lock ; "
#else
#define MPLOCKED
#endif

/*
 * The assembly is volatilized to demark potential before-and-after side
 * effects if an interrupt or SMP collision were to occur.  The primary
 * atomic instructions are MP safe, the nonlocked instructions are 
 * local-interrupt-safe (so we don't depend on C 'X |= Y' generating an
 * atomic instruction).
 *
 * +m - memory is read and written (=m - memory is only written)
 * iq - integer constant or %ax/%bx/%cx/%dx (ir = int constant or any reg)
 *	(Note: byte instructions only work on %ax,%bx,%cx, or %dx).  iq
 *	is good enough for our needs so don't get fancy.
 */

/* egcs 1.1.2+ version */
#define ATOMIC_ASM(NAME, TYPE, OP, V)			\
static __inline void					\
atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
{							\
	__asm __volatile(MPLOCKED OP			\
			 : "+m" (*p)			\
			 : "iq" (V)); 			\
}							\
static __inline void					\
atomic_##NAME##_##TYPE##_nonlocked(volatile u_##TYPE *p, u_##TYPE v)\
{							\
	__asm __volatile(OP				\
			 : "+m" (*p)			\
			 : "iq" (V)); 			\
}

#endif /* KLD_MODULE */

/* egcs 1.1.2+ version */
ATOMIC_ASM(set,	     char,  "orb %b1,%0",   v)
ATOMIC_ASM(clear,    char,  "andb %b1,%0", ~v)
ATOMIC_ASM(add,	     char,  "addb %b1,%0",  v)
ATOMIC_ASM(subtract, char,  "subb %b1,%0",  v)

ATOMIC_ASM(set,	     short, "orw %w1,%0",   v)
ATOMIC_ASM(clear,    short, "andw %w1,%0", ~v)
ATOMIC_ASM(add,	     short, "addw %w1,%0",  v)
ATOMIC_ASM(subtract, short, "subw %w1,%0",  v)

ATOMIC_ASM(set,	     int,   "orl %1,%0",   v)
ATOMIC_ASM(clear,    int,   "andl %1,%0", ~v)
ATOMIC_ASM(add,	     int,   "addl %1,%0",  v)
ATOMIC_ASM(subtract, int,   "subl %1,%0",  v)

ATOMIC_ASM(set,	     long,  "orl %1,%0",   v)
ATOMIC_ASM(clear,    long,  "andl %1,%0", ~v)
ATOMIC_ASM(add,	     long,  "addl %1,%0",  v)
ATOMIC_ASM(subtract, long,  "subl %1,%0",  v)

/*
 * atomic_poll_acquire_int(P)	Returns non-zero on success, 0 on failure
 * atomic_poll_release_int(P)
 *
 * Currently these are hacks just to support the NDIS driver.
 */

#if defined(KLD_MODULE)

extern int atomic_poll_acquire_int(volatile u_int *p);
extern void atomic_poll_release_int(volatile u_int *p);

#else

static __inline
int
atomic_poll_acquire_int(volatile u_int *p)
{
	u_int data;

	__asm __volatile(MPLOCKED "btsl $0,%0; setnc %%al; andl $255,%%eax" : "+m" (*p), "=a" (data));
	return(data);
}

static __inline
void
atomic_poll_release_int(volatile u_int *p)
{
	__asm __volatile("movl $0,%0" : "+m" (*p));
}

#endif

#endif /* ! _MACHINE_ATOMIC_H_ */