include/lttng/align.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _LTTNG_ALIGN_H
   8 #define _LTTNG_ALIGN_H
   9
  10 #include <lttng/bug.h>
  11
  12 /**
  13  * lttng_ust_offset_align - Calculate the offset needed to align an object on
  14  *                its natural alignment towards higher addresses.
  15  * @align_drift:  object offset from an "alignment"-aligned address.
  16  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  17  *
  18  * Returns the offset that must be added to align towards higher
  19  * addresses.
  20  */
  21 #define lttng_ust_offset_align(align_drift, alignment)                         \
  22         ({                                                                     \
  23                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  24                                    || ((alignment) & ((alignment) - 1)));      \
  25                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  26         })
  27
  28 /**
  29  * lttng_ust_offset_align_floor - Calculate the offset needed to align an
  30  *                object on its natural alignment towards lower addresses.
  31  * @align_drift:  object offset from an "alignment"-aligned address.
  32  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  33  *
  34  * Returns the offset that must be substracted to align towards lower addresses.
  35  */
  36 #define lttng_ust_offset_align_floor(align_drift, alignment)                   \
  37         ({                                                                     \
  38                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  39                                    || ((alignment) & ((alignment) - 1)));      \
  40                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  41         })
  42
  43 #endif /* _LTTNG_ALIGN_H */