src/common/align.hpp

   1 /*
   2  * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * SPDX-License-Identifier: MIT
   5  *
   6  */
   7
   8 #ifndef _LTTNG_ALIGN_H
   9 #define _LTTNG_ALIGN_H
  10
  11 #include "bug.hpp"
  12
  13 /*
  14  * Align value to the next multiple of align. Returns val if it already is a
  15  * multiple of align. Align must be a power of two.
  16  */
  17 #define __lttng_align_ceil_mask(v, mask) (((v) + (mask)) & ~(mask))
  18
  19 #define lttng_align_ceil(v, align) __lttng_align_ceil_mask(v, (__typeof__(v)) (align) -1)
  20
  21 /*
  22  * Align value to the previous multiple of align. Returns val if it already is a
  23  * multiple of align. Align must be a power of two.
  24  */
  25 #define __lttng_align_floor_mask(v, mask) ((v) & ~(mask))
  26
  27 #define lttng_align_floor(v, align) __lttng_align_floor_mask(v, (__typeof__(v)) (align) -1)
  28
  29 /**
  30  * lttng_offset_align - Calculate the offset needed to align an object on its natural
  31  *                alignment towards higher addresses.
  32  * @align_drift:  object offset from an "alignment"-aligned address.
  33  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  34  *
  35  * Returns the offset that must be added to align towards higher
  36  * addresses.
  37  */
  38 #define lttng_offset_align(align_drift, alignment)                                                \
  39         ({                                                                                        \
  40                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0 || ((alignment) & ((alignment) -1))); \
  41                 (((alignment) - (align_drift)) & ((alignment) -1));                               \
  42         })
  43
  44 /**
  45  * lttng_offset_align_floor - Calculate the offset needed to align an object
  46  *                      on its natural alignment towards lower addresses.
  47  * @align_drift:  object offset from an "alignment"-aligned address.
  48  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  49  *
  50  * Returns the offset that must be substracted to align towards lower addresses.
  51  */
  52 #define lttng_offset_align_floor(align_drift, alignment)                                          \
  53         ({                                                                                        \
  54                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0 || ((alignment) & ((alignment) -1))); \
  55                 (((align_drift) - (alignment)) & ((alignment) -1));                               \
  56         })
  57
  58 #endif /* _LTTNG_ALIGN_H */