1 files changed, 89 insertions, 0 deletions
diff --git a/cogl/cogl-flags.h b/cogl/cogl-flags.h
new file mode 100644
index 00000000..af07532f
--- /dev/null
+++ b/cogl/cogl-flags.h
@@ -0,0 +1,89 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2011 Intel Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Authors:
+ *   Neil Roberts <neil@linux.intel.com>
+ */
+
+#ifndef __COGL_FLAGS_H
+#define __COGL_FLAGS_H
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+/* These are macros used to implement a fixed-size array of bits. This
+   should be used instead of CoglBitmask when the maximum bit number
+   that will be set is known at compile time, for example when setting
+   for recording a set of known available features */
+
+/* The bits are stored in an array of unsigned ints. It would probably
+   make sense to use unsigned long instead because then on 64-bit
+   systems where it can handle 64-bits just as easily and it can test
+   more bits. However GDebugKey uses a guint for the mask and we need
+   to fit the masks into this */
+
+/* To use these macros, you would typically have an enum defining the
+   available bits with an extra last enum to define the maximum
+   value. Then to store the flags you would declare an array of
+   unsigned ints sized using COGL_FLAGS_N_INTS_FOR_SIZE, eg:
+
+   typedef enum { FEATURE_A, FEATURE_B, FEATURE_C, N_FEATURES } Features;
+
+   unsigned int feature_flags[COGL_FLAGS_N_INTS_FOR_SIZE (N_FEATURES)];
+*/
+
+#define COGL_FLAGS_N_INTS_FOR_SIZE(size)        \
+  (((size) +                                    \
+    (sizeof (unsigned int) * 8 - 1))            \
+   / (sizeof (unsigned int) * 8))
+
+/* @flag is expected to be constant so these should result in a
+   constant expression. This means that setting a flag is equivalent
+   to just setting in a bit in a global variable at a known
+   location */
+#define COGL_FLAGS_GET_INDEX(flag)              \
+  ((flag) / (sizeof (unsigned int) * 8))
+#define COGL_FLAGS_GET_MASK(flag)               \
+  (1U << ((unsigned int) (flag) &               \
+          (sizeof (unsigned int) * 8 - 1)))
+
+#define COGL_FLAGS_GET(array, flag)             \
+  (!!((array)[COGL_FLAGS_GET_INDEX (flag)] &    \
+      COGL_FLAGS_GET_MASK (flag)))
+
+/* The expectation here is that @value will be constant so the if
+   statement will be optimised out */
+#define COGL_FLAGS_SET(array, flag, value)      \
+  G_STMT_START {                                \
+    if (value)                                  \
+      ((array)[COGL_FLAGS_GET_INDEX (flag)] |=  \
+       COGL_FLAGS_GET_MASK (flag));             \
+    else                                        \
+      ((array)[COGL_FLAGS_GET_INDEX (flag)] &=  \
+       ~COGL_FLAGS_GET_MASK (flag));            \
+  } G_STMT_END
+
+G_END_DECLS
+
+#endif /* __COGL_FLAGS_H */
+