about summary refs log tree commit diff
path: root/sysdeps/i386
diff options
context:
space:
mode:
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/i386
parent5132931e18d50a1caf7399aa46dafd0142a7c7ae (diff)
downloadglibc-f79466a8e909930237d882da8916bbbb1401edf6.tar.gz
glibc-f79466a8e909930237d882da8916bbbb1401edf6.tar.xz
glibc-f79466a8e909930237d882da8916bbbb1401edf6.zip
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/i386')
-rw-r--r--sysdeps/i386/i486/bits/atomic.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/sysdeps/i386/i486/bits/atomic.h b/sysdeps/i386/i486/bits/atomic.h
index 87739c6cc6..e22e560a38 100644
--- a/sysdeps/i386/i486/bits/atomic.h
+++ b/sysdeps/i386/i486/bits/atomic.h
@@ -119,6 +119,29 @@ typedef uintmax_t uatomic_max_t;
 #endif
 
 
+/* 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								      \
+       {								      \
+	 result = 0;							      \
+	 abort ();							      \
+       }								      \
+     result; })
+
+
 #define atomic_exchange_and_add(mem, value) \
   ({ __typeof (*mem) result;						      \
      __typeof (value) addval = (value);					      \