[Mesa-dev] [PATCH 1/4] util: add new bitfield_assert.h header

[Brian Paul]

Contains a macro for checking that bitfields are large enough to
hold the largest expected value.
---
 src/util/bitfield_assert.h | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 src/util/bitfield_assert.h

diff --git a/src/util/bitfield_assert.h b/src/util/bitfield_assert.h
new file mode 100644
index 0000000..dab2b21
--- /dev/null
+++ b/src/util/bitfield_assert.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright © 2017 VMware, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+
+#ifndef BITFIELD_ASSERT_H
+#define BITFIELD_ASSERT_H
+
+
+#include <assert.h>
+
+
+/**
+ * Check that STRUCT::FIELD can hold MAXVAL.  We use a lot of bitfields
+ * in Mesa/gallium.  We have to be sure they're of sufficient size to
+ * hold the largest expected value.
+ * Note that with MSVC, enums are signed and enum bitfields need one extra
+ * high bit (always zero) to ensure the max value is handled correctly.
+ * This macro will detect that with MSVC, but not GCC.
+ */
+#define ASSERT_BITFIELD_SIZE(STRUCT, FIELD, MAXVAL) \
+   do { \
+      STRUCT s; \
+      s.FIELD = (MAXVAL); \
+      assert((int) s.FIELD == (MAXVAL) && "Insufficient bitfield size!"); \
+   } while (0)
+
+
+
+#endif /* BITFIELD_ASSERT_H */
-- 
1.9.1