From f354dbfd86da3630a8255742b26f41788ac10194 Mon Sep 17 00:00:00 2001
From: jkim <jkim@FreeBSD.org>
Date: Wed, 21 Aug 2013 22:03:06 +0000
Subject: Implement atomic_swap() and atomic_testandset().

Reviewed by:	arch, bde, jilles, kib
---
 sys/i386/include/atomic.h | 62 ++++++++++++++++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 19 deletions(-)

(limited to 'sys/i386/include')

diff --git a/sys/i386/include/atomic.h b/sys/i386/include/atomic.h
index f782295..0d1738c 100644
--- a/sys/i386/include/atomic.h
+++ b/sys/i386/include/atomic.h
@@ -54,12 +54,14 @@
  * 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_swap_int(P, V)	(return (*(u_int *)(P)); *(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_swap_long(P, V)	(return (*(u_long *)(P)); *(u_long *)(P) = (V);)
  * atomic_readandclear_long(P)	(return (*(u_long *)(P)); *(u_long *)(P) = 0;)
  */
 
@@ -78,6 +80,7 @@ void atomic_##NAME##_barr_##TYPE(volatile u_##TYPE *p, u_##TYPE v)
 
 int	atomic_cmpset_int(volatile u_int *dst, u_int expect, u_int src);
 u_int	atomic_fetchadd_int(volatile u_int *p, u_int v);
+int	atomic_testandset_int(volatile u_int *p, u_int v);
 
 #define	ATOMIC_LOAD(TYPE, LOP)					\
 u_##TYPE	atomic_load_acq_##TYPE(volatile u_##TYPE *p)
@@ -275,6 +278,23 @@ atomic_fetchadd_int(volatile u_int *p, u_int v)
 	return (v);
 }
 
+static __inline int
+atomic_testandset_int(volatile u_int *p, u_int v)
+{
+	u_char res;
+
+	__asm __volatile(
+	"	" MPLOCKED "		"
+	"	btsl	%2,%1 ;		"
+	"	setc	%0 ;		"
+	"# atomic_testandset_int"
+	: "=q" (res),			/* 0 */
+	  "+m" (*p)			/* 1 */
+	: "Ir" (v & 0x1f)		/* 2 */
+	: "cc");
+	return (res);
+}
+
 /*
  * We assume that a = b will do atomic loads and stores.  Due to the
  * IA32 memory model, a simple store guarantees release semantics.
@@ -386,43 +406,40 @@ atomic_fetchadd_long(volatile u_long *p, u_long v)
 	return (atomic_fetchadd_int((volatile u_int *)p, (u_int)v));
 }
 
-/* Read the current value and store a zero in the destination. */
+static __inline int
+atomic_testandset_long(volatile u_long *p, u_int v)
+{
+
+	return (atomic_testandset_int((volatile u_int *)p, v));
+}
+
+/* Read the current value and store a new value in the destination. */
 #ifdef __GNUCLIKE_ASM
 
 static __inline u_int
-atomic_readandclear_int(volatile u_int *p)
+atomic_swap_int(volatile u_int *p, u_int v)
 {
-	u_int res;
 
-	res = 0;
 	__asm __volatile(
 	"	xchgl	%1,%0 ;		"
-	"# atomic_readandclear_int"
-	: "+r" (res),			/* 0 */
+	"# atomic_swap_int"
+	: "+r" (v),			/* 0 */
 	  "+m" (*p));			/* 1 */
 
-	return (res);
+	return (v);
 }
 
 static __inline u_long
-atomic_readandclear_long(volatile u_long *p)
+atomic_swap_long(volatile u_long *p, u_long v)
 {
-	u_long res;
 
-	res = 0;
-	__asm __volatile(
-	"	xchgl	%1,%0 ;		"
-	"# atomic_readandclear_long"
-	: "+r" (res),			/* 0 */
-	  "+m" (*p));			/* 1 */
-
-	return (res);
+	return (atomic_swap_int((volatile u_int *)p, (u_int)v));
 }
 
 #else /* !__GNUCLIKE_ASM */
 
-u_int	atomic_readandclear_int(volatile u_int *p);
-u_long	atomic_readandclear_long(volatile u_long *p);
+u_int	atomic_swap_int(volatile u_int *p, u_int v);
+u_long	atomic_swap_long(volatile u_long *p, u_long v);
 
 #endif /* __GNUCLIKE_ASM */
 
@@ -466,6 +483,9 @@ u_long	atomic_readandclear_long(volatile u_long *p);
 #define	atomic_cmpset_acq_long		atomic_cmpset_long
 #define	atomic_cmpset_rel_long		atomic_cmpset_long
 
+#define	atomic_readandclear_int(p)	atomic_swap_int(p, 0)
+#define	atomic_readandclear_long(p)	atomic_swap_long(p, 0)
+
 /* Operations on 8-bit bytes. */
 #define	atomic_set_8		atomic_set_char
 #define	atomic_set_acq_8	atomic_set_acq_char
@@ -516,8 +536,10 @@ u_long	atomic_readandclear_long(volatile u_long *p);
 #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_swap_32		atomic_swap_int
 #define	atomic_readandclear_32	atomic_readandclear_int
 #define	atomic_fetchadd_32	atomic_fetchadd_int
+#define	atomic_testandset_32	atomic_testandset_int
 
 /* Operations on pointers. */
 #define	atomic_set_ptr(p, v) \
@@ -556,6 +578,8 @@ u_long	atomic_readandclear_long(volatile u_long *p);
 #define	atomic_cmpset_rel_ptr(dst, old, new) \
 	atomic_cmpset_rel_int((volatile u_int *)(dst), (u_int)(old), \
 	    (u_int)(new))
+#define	atomic_swap_ptr(p, v) \
+	atomic_swap_int((volatile u_int *)(p), (u_int)(v))
 #define	atomic_readandclear_ptr(p) \
 	atomic_readandclear_int((volatile u_int *)(p))
 
-- 
cgit v1.1