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authorUlrich Drepper <drepper@redhat.com>2003-03-20 10:18:24 +0000
committerUlrich Drepper <drepper@redhat.com>2003-03-20 10:18:24 +0000
commitf79466a8e909930237d882da8916bbbb1401edf6 (patch)
tree460afefe452e8550b56d9a01d90dc129012dfd27 /sysdeps/x86_64
parent5132931e18d50a1caf7399aa46dafd0142a7c7ae (diff)
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Update.
2003-03-20  Ulrich Drepper  <drepper@redhat.com>

	* include/atomic.h: Define atomic_exchange and
	atomic_decrement_if_positive if not already defined.  Add some
	__builtin_expect.
	* sysdeps/i386/i486/bits/atomic.h: Define atomic_exchange.
	* sysdeps/x86_64/bits/atomic.h: Likewise.
	* sysdeps/ia64/bits/atomic.h: Pretty printing.  Define atomic_exchange.
	* sysdeps/powerpc/bits/atomic.h: Pretty printing.  Define
	atomic_exchange, atomic_exchange_and_add, and
	atomic_decrement_if_positive
Diffstat (limited to 'sysdeps/x86_64')
-rw-r--r--sysdeps/x86_64/bits/atomic.h24
1 files changed, 23 insertions, 1 deletions
diff --git a/sysdeps/x86_64/bits/atomic.h b/sysdeps/x86_64/bits/atomic.h
index f72f16c501..22d3ab0267 100644
--- a/sysdeps/x86_64/bits/atomic.h
+++ b/sysdeps/x86_64/bits/atomic.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -84,6 +84,28 @@ typedef uintmax_t uatomic_max_t;
      ret; })
 
 
+/* Note that we need no lock prefix.  */
+#define atomic_exchange(mem, newvalue) \
+  ({ __typeof (*mem) result;						      \
+     if (sizeof (*mem) == 1)						      \
+       __asm __volatile ("xchgb %b0, %1"				      \
+			 : "=r" (result), "=m" (*mem)			      \
+			 : "0" (newvalue), "1" (*mem));			      \
+     else if (sizeof (*mem) == 2)					      \
+       __asm __volatile ("xchgw %w0, %1"				      \
+			 : "=r" (result), "=m" (*mem)			      \
+			 : "0" (newvalue), "1" (*mem));			      \
+     else if (sizeof (*mem) == 4)					      \
+       __asm __volatile ("xchgl %0, %1"					      \
+			 : "=r" (result), "=m" (*mem)			      \
+			 : "0" (newvalue), "1" (*mem));			      \
+     else								      \
+       __asm __volatile ("xchgq %q0, %1"				      \
+			 : "=r" (result), "=m" (*mem)			      \
+			 : "0" (newvalue), "1" (*mem));			      \
+     result; })
+
+
 #define atomic_exchange_and_add(mem, value) \
   ({ __typeof (*mem) result;						      \
      if (sizeof (*mem) == 1)						      \