include/lttng/align.h

   1 #ifndef _UST_ALIGN_H
   2 #define _UST_ALIGN_H
   3
   4 /*
   5  * lttng/align.h
   6  *
   7  * (C) Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Dual LGPL v2.1/GPL v2 license.
  10  */
  11
  12 #include <lttng/bug.h>
  13
  14 /*
  15  * Align pointer on natural object alignment.
  16  */
  17 #define object_align(obj)       PTR_ALIGN(obj, __alignof__(*(obj)))
  18 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  19
  20 /**
  21  * offset_align - Calculate the offset needed to align an object on its natural
  22  *                alignment towards higher addresses.
  23  * @align_drift:  object offset from an "alignment"-aligned address.
  24  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  25  *
  26  * Returns the offset that must be added to align towards higher
  27  * addresses.
  28  */
  29 #define offset_align(align_drift, alignment)                                   \
  30         ({                                                                     \
  31                 BUILD_RUNTIME_BUG_ON((alignment) == 0                          \
  32                                    || ((alignment) & ((alignment) - 1)));      \
  33                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  34         })
  35
  36 /**
  37  * offset_align_floor - Calculate the offset needed to align an object
  38  *                      on its natural alignment towards lower addresses.
  39  * @align_drift:  object offset from an "alignment"-aligned address.
  40  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  41  *
  42  * Returns the offset that must be substracted to align towards lower addresses.
  43  */
  44 #define offset_align_floor(align_drift, alignment)                             \
  45         ({                                                                     \
  46                 BUILD_RUNTIME_BUG_ON((alignment) == 0                          \
  47                                    || ((alignment) & ((alignment) - 1)));      \
  48                 (((align_drift) - (alignment)) & ((alignment) - 1);            \
  49         })
  50
  51 #endif /* _UST_ALIGN_H */