text: /*-
   * 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/amd64/include/atomic.h,v 1.39 2005/09/27 17:39:10 jhb Exp $
   */
  #ifndef _MACHINE_ATOMIC_H_
  #define	_MACHINE_ATOMIC_H_
  
  #ifndef _SYS_CDEFS_H_
  #error this file needs sys/cdefs.h as a prerequisite
  #endif
  
  /*
   * 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_readandclear_int(P)	(return  *(u_int*)P; *(u_int*)P = 0;)
   *
   * 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))
   * atomic_readandclear_long(P)	(return  *(u_long*)P; *(u_long*)P = 0;)
   */
  
  /*
   * 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) || !(defined(__GNUCLIKE_ASM) && defined(__CC_SUPPORTS___INLINE))
  #define	ATOMIC_ASM(NAME, TYPE, OP, CONS, V)			\
  void atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
  
  int atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src);
  int atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src);
  u_int atomic_fetchadd_int(volatile u_int *p, u_int v);
  
  #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)			\
  u_##TYPE	atomic_load_acq_##TYPE(volatile u_##TYPE *p);	\
  void		atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
  
  #else /* !KLD_MODULE && __GNUCLIKE_ASM && __CC_SUPPORTS___INLINE */
  
  /*
   * For userland, assume the SMP case and use lock prefixes so that
   * the binaries will run on both types of systems.
   */
  #if defined(SMP) || !defined(_KERNEL)
  #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.
   */
  #define	ATOMIC_ASM(NAME, TYPE, OP, CONS, V)		\
  static __inline void					\
  atomic_##NAME##_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  {							\
  	__asm __volatile(__XSTRING(MPLOCKED) OP		\
  			 : "=m" (*p)			\
  			 : CONS (V), "m" (*p));		\
  }							\
  struct __hack
  
  /*
   * Atomic compare and set, used by the mutex functions
   *
   * if (*dst == exp) *dst = src (all 32 bit words)
   *
   * Returns 0 on failure, non-zero on success
   */
  
  static __inline int
  atomic_cmpset_int(volatile u_int *dst, u_int exp, u_int src)
  {
  	int res = exp;
  
  	__asm __volatile (
  	"	" __XSTRING(MPLOCKED) "	"
  	"	cmpxchgl %2,%1 ;	"
  	"       setz	%%al ;		"
  	"	movzbl	%%al,%0 ;	"
  	"1:				"
  	"# atomic_cmpset_int"
  	: "+a" (res), 			/* 0 (result) */
  	  "=m" (*dst)			/* 1 */
  	: "r" (src),			/* 2 */
  	  "m" (*dst)			/* 3 */
  	: "memory");
  
  	return (res);
  }
  
  static __inline int
  atomic_cmpset_long(volatile u_long *dst, u_long exp, u_long src)
  {
  	long res = exp;
  
  	__asm __volatile (
  	"	" __XSTRING(MPLOCKED) "	"
  	"	cmpxchgq %2,%1 ;	"
  	"       setz	%%al ;		"
  	"	movzbq	%%al,%0 ;	"
  	"1:				"
  	"# atomic_cmpset_long"
  	: "+a" (res),			/* 0 (result) */
  	  "=m" (*dst)			/* 1 */
  	: "r" (src),			/* 2 */
  	  "m" (*dst)			/* 3 */
  	: "memory");
  
  	return (res);
  }
  
  /*
   * Atomically add the value of v to the integer pointed to by p and return
   * the previous value of *p.
   */
  static __inline u_int
  atomic_fetchadd_int(volatile u_int *p, u_int v)
  {
  
  	__asm __volatile (
  	"	" __XSTRING(MPLOCKED) "	"
  	"	xaddl	%0, %1 ;	"
  	"# atomic_fetchadd_int"
  	: "+r" (v),			/* 0 (result) */
  	  "=m" (*p)			/* 1 */
  	: "m" (*p));			/* 2 */
  
  	return (v);
  }
  
  #if defined(_KERNEL) && !defined(SMP)
  
  /*
   * We assume that a = b will do atomic loads and stores.  However, on a
   * PentiumPro or higher, reads may pass writes, so for that case we have
   * to use a serializing instruction (i.e. with LOCK) to do the load in
   * SMP kernels.  For UP kernels, however, the cache of the single processor
   * is always consistent, so we don't need any memory barriers.
   */
  #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)		\
  static __inline u_##TYPE				\
  atomic_load_acq_##TYPE(volatile u_##TYPE *p)		\
  {							\
  	return (*p);					\
  }							\
  							\
  static __inline void					\
  atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  {							\
  	*p = v;						\
  }							\
  struct __hack
  
  #else /* defined(SMP) */
  
  #define	ATOMIC_STORE_LOAD(TYPE, LOP, SOP)		\
  static __inline u_##TYPE				\
  atomic_load_acq_##TYPE(volatile u_##TYPE *p)		\
  {							\
  	u_##TYPE res;					\
  							\
  	__asm __volatile(__XSTRING(MPLOCKED) LOP	\
  	: "=a" (res),			/* 0 (result) */\
  	  "=m" (*p)			/* 1 */		\
  	: "m" (*p)			/* 2 */		\
  	: "memory");				 	\
  							\
  	return (res);					\
  }							\
  							\
  /*							\
   * The XCHG instruction asserts LOCK automagically.	\
   */							\
  static __inline void					\
  atomic_store_rel_##TYPE(volatile u_##TYPE *p, u_##TYPE v)\
  {							\
  	__asm __volatile(SOP				\
  	: "=m" (*p),			/* 0 */		\
  	  "+r" (v)			/* 1 */		\
  	: "m" (*p));			/* 2 */		\
  }							\
  struct __hack
  
  #endif /* SMP */
  
  #endif /* KLD_MODULE || !(__GNUCLIKE_ASM && __CC_SUPPORTS___INLINE) */
  
  ATOMIC_ASM(set,	     char,  "orb %b1,%0",  "iq",  v);
  ATOMIC_ASM(clear,    char,  "andb %b1,%0", "iq", ~v);
  ATOMIC_ASM(add,	     char,  "addb %b1,%0", "iq",  v);
  ATOMIC_ASM(subtract, char,  "subb %b1,%0", "iq",  v);
  
  ATOMIC_ASM(set,	     short, "orw %w1,%0",  "ir",  v);
  ATOMIC_ASM(clear,    short, "andw %w1,%0", "ir", ~v);
  ATOMIC_ASM(add,	     short, "addw %w1,%0", "ir",  v);
  ATOMIC_ASM(subtract, short, "subw %w1,%0", "ir",  v);
  
  ATOMIC_ASM(set,	     int,   "orl %1,%0",   "ir",  v);
  ATOMIC_ASM(clear,    int,   "andl %1,%0",  "ir", ~v);
  ATOMIC_ASM(add,	     int,   "addl %1,%0",  "ir",  v);
  ATOMIC_ASM(subtract, int,   "subl %1,%0",  "ir",  v);
  
  ATOMIC_ASM(set,	     long,  "orq %1,%0",   "ir",  v);
  ATOMIC_ASM(clear,    long,  "andq %1,%0",  "ir", ~v);
  ATOMIC_ASM(add,	     long,  "addq %1,%0",  "ir",  v);
  ATOMIC_ASM(subtract, long,  "subq %1,%0",  "ir",  v);
  
  ATOMIC_STORE_LOAD(char,	"cmpxchgb %b0,%1", "xchgb %b1,%0");
  ATOMIC_STORE_LOAD(short,"cmpxchgw %w0,%1", "xchgw %w1,%0");
  ATOMIC_STORE_LOAD(int,	"cmpxchgl %0,%1",  "xchgl %1,%0");
  ATOMIC_STORE_LOAD(long,	"cmpxchgq %0,%1",  "xchgq %1,%0");
  
  #undef ATOMIC_ASM
  #undef ATOMIC_STORE_LOAD
  
  #if !defined(WANT_FUNCTIONS)
  
  /* Read the current value and store a zero in the destination. */
  #if defined(__GNUCLIKE_ASM) && defined(__CC_SUPPORTS___INLINE)
  
  static __inline u_int
  atomic_readandclear_int(volatile u_int *addr)
  {
  	u_int result;
  
  	result = 0;
  	__asm __volatile (
  	"	xchgl	%1,%0 ;		"
  	"# atomic_readandclear_int"
  	: "+r" (result),		/* 0 (result) */
  	  "=m" (*addr)			/* 1 (addr) */
  	: "m" (*addr));
  
  	return (result);
  }
  
  static __inline u_long
  atomic_readandclear_long(volatile u_long *addr)
  {
  	u_long result;
  
  	result = 0;
  	__asm __volatile (
  	"	xchgq	%1,%0 ;		"
  	"# atomic_readandclear_long"
  	: "+r" (result),		/* 0 (result) */
  	  "=m" (*addr)			/* 1 (addr) */
  	: "m" (*addr));
  
  	return (result);
  }
  
  #else /* !(__GNUCLIKE_ASM && __CC_SUPPORTS___INLINE) */
  
  u_int	atomic_readandclear_int(volatile u_int *);
  u_long	atomic_readandclear_long(volatile u_long *);
  
  #endif /* __GNUCLIKE_ASM && __CC_SUPPORTS___INLINE */
  
  /* Acquire and release variants are identical to the normal ones. */
  #define	atomic_set_acq_char		atomic_set_char
  #define	atomic_set_rel_char		atomic_set_char
  #define	atomic_clear_acq_char		atomic_clear_char
  #define	atomic_clear_rel_char		atomic_clear_char
  #define	atomic_add_acq_char		atomic_add_char
  #define	atomic_add_rel_char		atomic_add_char
  #define	atomic_subtract_acq_char	atomic_subtract_char
  #define	atomic_subtract_rel_char	atomic_subtract_char
  
  #define	atomic_set_acq_short		atomic_set_short
  #define	atomic_set_rel_short		atomic_set_short
  #define	atomic_clear_acq_short		atomic_clear_short
  #define	atomic_clear_rel_short		atomic_clear_short
  #define	atomic_add_acq_short		atomic_add_short
  #define	atomic_add_rel_short		atomic_add_short
  #define	atomic_subtract_acq_short	atomic_subtract_short
  #define	atomic_subtract_rel_short	atomic_subtract_short
  
  #define	atomic_set_acq_int		atomic_set_int
  #define	atomic_set_rel_int		atomic_set_int
  #define	atomic_clear_acq_int		atomic_clear_int
  #define	atomic_clear_rel_int		atomic_clear_int
  #define	atomic_add_acq_int		atomic_add_int
  #define	atomic_add_rel_int		atomic_add_int
  #define	atomic_subtract_acq_int		atomic_subtract_int
  #define	atomic_subtract_rel_int		atomic_subtract_int
  #define	atomic_cmpset_acq_int		atomic_cmpset_int
  #define	atomic_cmpset_rel_int		atomic_cmpset_int
  
  #define	atomic_set_acq_long		atomic_set_long
  #define	atomic_set_rel_long		atomic_set_long
  #define	atomic_clear_acq_long		atomic_clear_long
  #define	atomic_clear_rel_long		atomic_clear_long
  #define	atomic_add_acq_long		atomic_add_long
  #define	atomic_add_rel_long		atomic_add_long
  #define	atomic_subtract_acq_long	atomic_subtract_long
  #define	atomic_subtract_rel_long	atomic_subtract_long
  #define	atomic_cmpset_acq_long		atomic_cmpset_long
  #define	atomic_cmpset_rel_long		atomic_cmpset_long
  
  /* Operations on 8-bit bytes. */
  #define	atomic_set_8		atomic_set_char
  #define	atomic_set_acq_8	atomic_set_acq_char
  #define	atomic_set_rel_8	atomic_set_rel_char
  #define	atomic_clear_8		atomic_clear_char
  #define	atomic_clear_acq_8	atomic_clear_acq_char
  #define	atomic_clear_rel_8	atomic_clear_rel_char
  #define	atomic_add_8		atomic_add_char
  #define	atomic_add_acq_8	atomic_add_acq_char
  #define	atomic_add_rel_8	atomic_add_rel_char
  #define	atomic_subtract_8	atomic_subtract_char
  #define	atomic_subtract_acq_8	atomic_subtract_acq_char
  #define	atomic_subtract_rel_8	atomic_subtract_rel_char
  #define	atomic_load_acq_8	atomic_load_acq_char
  #define	atomic_store_rel_8	atomic_store_rel_char
  
  /* Operations on 16-bit words. */
  #define	atomic_set_16		atomic_set_short
  #define	atomic_set_acq_16	atomic_set_acq_short
  #define	atomic_set_rel_16	atomic_set_rel_short
  #define	atomic_clear_16		atomic_clear_short
  #define	atomic_clear_acq_16	atomic_clear_acq_short
  #define	atomic_clear_rel_16	atomic_clear_rel_short
  #define	atomic_add_16		atomic_add_short
  #define	atomic_add_acq_16	atomic_add_acq_short
  #define	atomic_add_rel_16	atomic_add_rel_short
  #define	atomic_subtract_16	atomic_subtract_short
  #define	atomic_subtract_acq_16	atomic_subtract_acq_short
  #define	atomic_subtract_rel_16	atomic_subtract_rel_short
  #define	atomic_load_acq_16	atomic_load_acq_short
  #define	atomic_store_rel_16	atomic_store_rel_short
  
  /* Operations on 32-bit double words. */
  #define	atomic_set_32		atomic_set_int
  #define	atomic_set_acq_32	atomic_set_acq_int
  #define	atomic_set_rel_32	atomic_set_rel_int
  #define	atomic_clear_32		atomic_clear_int
  #define	atomic_clear_acq_32	atomic_clear_acq_int
  #define	atomic_clear_rel_32	atomic_clear_rel_int
  #define	atomic_add_32		atomic_add_int
  #define	atomic_add_acq_32	atomic_add_acq_int
  #define	atomic_add_rel_32	atomic_add_rel_int
  #define	atomic_subtract_32	atomic_subtract_int
  #define	atomic_subtract_acq_32	atomic_subtract_acq_int
  #define	atomic_subtract_rel_32	atomic_subtract_rel_int
  #define	atomic_load_acq_32	atomic_load_acq_int
  #define	atomic_store_rel_32	atomic_store_rel_int
  #define	atomic_cmpset_32	atomic_cmpset_int
  #define	atomic_cmpset_acq_32	atomic_cmpset_acq_int
  #define	atomic_cmpset_rel_32	atomic_cmpset_rel_int
  #define	atomic_readandclear_32	atomic_readandclear_int
  #define	atomic_fetchadd_32	atomic_fetchadd_int
  
  /* Operations on 64-bit quad words. */
  #define	atomic_set_64		atomic_set_long
  #define	atomic_set_acq_64	atomic_set_acq_long
  #define	atomic_set_rel_64	atomic_set_rel_long
  #define	atomic_clear_64		atomic_clear_long
  #define	atomic_clear_acq_64	atomic_clear_acq_long
  #define	atomic_clear_rel_64	atomic_clear_rel_long
  #define	atomic_add_64		atomic_add_long
  #define	atomic_add_acq_64	atomic_add_acq_long
  #define	atomic_add_rel_64	atomic_add_rel_long
  #define	atomic_subtract_64	atomic_subtract_long
  #define	atomic_subtract_acq_64	atomic_subtract_acq_long
  #define	atomic_subtract_rel_64	atomic_subtract_rel_long
  #define	atomic_load_acq_64	atomic_load_acq_long
  #define	atomic_store_rel_64	atomic_store_rel_long
  #define	atomic_cmpset_64	atomic_cmpset_long
  #define	atomic_cmpset_acq_64	atomic_cmpset_acq_long
  #define	atomic_cmpset_rel_64	atomic_cmpset_rel_long
  #define	atomic_readandclear_64	atomic_readandclear_long
  
  /* Operations on pointers. */
  #define	atomic_set_ptr		atomic_set_long
  #define	atomic_set_acq_ptr	atomic_set_acq_long
  #define	atomic_set_rel_ptr	atomic_set_rel_long
  #define	atomic_clear_ptr	atomic_clear_long
  #define	atomic_clear_acq_ptr	atomic_clear_acq_long
  #define	atomic_clear_rel_ptr	atomic_clear_rel_long
  #define	atomic_add_ptr		atomic_add_long
  #define	atomic_add_acq_ptr	atomic_add_acq_long
  #define	atomic_add_rel_ptr	atomic_add_rel_long
  #define	atomic_subtract_ptr	atomic_subtract_long
  #define	atomic_subtract_acq_ptr	atomic_subtract_acq_long
  #define	atomic_subtract_rel_ptr	atomic_subtract_rel_long
  #define	atomic_load_acq_ptr	atomic_load_acq_long
  #define	atomic_store_rel_ptr	atomic_store_rel_long
  #define	atomic_cmpset_ptr	atomic_cmpset_long
  #define	atomic_cmpset_acq_ptr	atomic_cmpset_acq_long
  #define	atomic_cmpset_rel_ptr	atomic_cmpset_rel_long
  #define	atomic_readandclear_ptr	atomic_readandclear_long
  
  #endif	/* !defined(WANT_FUNCTIONS) */
  #endif /* ! _MACHINE_ATOMIC_H_ */
  