[cairo-atomic] Introduce atomic ops.

Test for the availability of the Intel __sync_* atomic primitives and
use them to define a few operations useful for reference counting -
providing a generic interface that may be targeted at more architectures
in the future. If no atomic primitives are available, use a mutex based
variant. If the contention on that mutex is too high, we can consider
using an array of mutexes using the address of the atomic variable as
the hash.

1 files changed, 81 insertions, 0 deletions

diff --git a/src/cairo-atomic-private.h b/src/cairo-atomic-private.h
new file mode 100644
index 00000000..3577e0d3
--- /dev/null
+++ b/src/cairo-atomic-private.h
@@ -0,0 +1,81 @@
+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2007 Chris Wilson
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is University of Southern
+ * California.
+ *
+ * Contributor(s):
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#ifndef CAIRO_ATOMIC_PRIVATE_H
+#define CAIRO_ATOMIC_PRIVATE_H
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+CAIRO_BEGIN_DECLS
+
+#define CAIRO_HAS_ATOMIC_OPS 1
+
+#if CAIRO_HAS_INTEL_ATOMIC_PRIMITIVES
+
+typedef int cairo_atomic_int_t;
+
+# define _cairo_atomic_int_inc(x) ((void) __sync_fetch_and_add(x, 1))
+# define _cairo_atomic_int_dec_and_test(x) (__sync_fetch_and_add(x, -1) == 1)
+# define _cairo_atomic_int_get(x) (*x)
+# define _cairo_atomic_int_set(x, value) ((*x) = value)
+
+#else
+
+# include "cairo-compiler-private.h"
+
+# undef CAIRO_HAS_ATOMIC_OPS
+
+typedef int cairo_atomic_int_t;
+
+cairo_private void
+_cairo_atomic_int_inc (int *x);
+
+cairo_private cairo_bool_t
+_cairo_atomic_int_dec_and_test (int *x);
+
+cairo_private int
+_cairo_atomic_int_get (int *x);
+
+cairo_private void
+_cairo_atomic_int_set (int *x, int value);
+
+#endif
+
+CAIRO_END_DECLS
+
+#endif