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) \
  20         __lttng_align_ceil_mask(v, (__typeof__(v)) (align) - 1)
  21
  22 /*
  23  * Align value to the previous multiple of align. Returns val if it already is a
  24  * multiple of align. Align must be a power of two.
  25  */
  26 #define __lttng_align_floor_mask(v, mask)       ((v) & ~(mask))
  27
  28 #define lttng_align_floor(v, align) \
  29         __lttng_align_floor_mask(v, (__typeof__(v)) (align) - 1)
  30
  31 /**
  32  * lttng_offset_align - Calculate the offset needed to align an object on its natural
  33  *                alignment towards higher addresses.
  34  * @align_drift:  object offset from an "alignment"-aligned address.
  35  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  36  *
  37  * Returns the offset that must be added to align towards higher
  38  * addresses.
  39  */
  40 #define lttng_offset_align(align_drift, alignment)                                     \
  41         ({                                                                     \
  42                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  43                                    || ((alignment) & ((alignment) - 1)));      \
  44                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  45         })
  46
  47 /**
  48  * lttng_offset_align_floor - Calculate the offset needed to align an object
  49  *                      on its natural alignment towards lower addresses.
  50  * @align_drift:  object offset from an "alignment"-aligned address.
  51  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  52  *
  53  * Returns the offset that must be substracted to align towards lower addresses.
  54  */
  55 #define lttng_offset_align_floor(align_drift, alignment)                               \
  56         ({                                                                     \
  57                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  58                                    || ((alignment) & ((alignment) - 1)));      \
  59                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  60         })
  61
  62 #endif /* _LTTNG_ALIGN_H */