[lttng-dev] [PATCH 05/20] lttng: offset alignment header

[Mathieu Desnoyers]

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
 drivers/staging/lttng/lib/align.h |   61 +++++++++++++++++++++++++++++++++++++
 1 files changed, 61 insertions(+), 0 deletions(-)
 create mode 100644 drivers/staging/lttng/lib/align.h

diff --git a/drivers/staging/lttng/lib/align.h b/drivers/staging/lttng/lib/align.h
new file mode 100644
index 0000000..0b86100
--- /dev/null
+++ b/drivers/staging/lttng/lib/align.h
@@ -0,0 +1,61 @@
+#ifndef _LTTNG_ALIGN_H
+#define _LTTNG_ALIGN_H
+
+/*
+ * lib/align.h
+ *
+ * (C) Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include "bug.h"
+
+#define ALIGN_FLOOR(x, a)	__ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
+#define __ALIGN_FLOOR_MASK(x, mask)	((x) & ~(mask))
+#define PTR_ALIGN_FLOOR(p, a) \
+			((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
+
+/*
+ * Align pointer on natural object alignment.
+ */
+#define object_align(obj)	PTR_ALIGN(obj, __alignof__(*(obj)))
+#define object_align_floor(obj)	PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
+
+/**
+ * offset_align - Calculate the offset needed to align an object on its natural
+ *                alignment towards higher addresses.
+ * @align_drift:  object offset from an "alignment"-aligned address.
+ * @alignment:    natural object alignment. Must be non-zero, power of 2.
+ *
+ * Returns the offset that must be added to align towards higher
+ * addresses.
+ */
+#define offset_align(align_drift, alignment)				       \
+	({								       \
+		BUILD_RUNTIME_BUG_ON((alignment) == 0			       \
+				   || ((alignment) & ((alignment) - 1)));      \
+		(((alignment) - (align_drift)) & ((alignment) - 1));	       \
+	})
+
+/**
+ * offset_align_floor - Calculate the offset needed to align an object
+ *                      on its natural alignment towards lower addresses.
+ * @align_drift:  object offset from an "alignment"-aligned address.
+ * @alignment:    natural object alignment. Must be non-zero, power of 2.
+ *
+ * Returns the offset that must be substracted to align towards lower addresses.
+ */
+#define offset_align_floor(align_drift, alignment)			       \
+	({								       \
+		BUILD_RUNTIME_BUG_ON((alignment) == 0			       \
+				   || ((alignment) & ((alignment) - 1)));      \
+		(((align_drift) - (alignment)) & ((alignment) - 1);	       \
+	})
+
+#endif /* __KERNEL__ */
+
+#endif
-- 
1.7.2.5