include/lttng/align.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng/align.h
   4  *
   5  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  */
   7
   8 #ifndef _LTTNG_ALIGN_H
   9 #define _LTTNG_ALIGN_H
  10
  11 #ifdef __KERNEL__
  12
  13 #include <linux/types.h>
  14 #include <lttng/bug.h>
  15
  16 #define ALIGN_FLOOR(x, a)       __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
  17 #define __ALIGN_FLOOR_MASK(x, mask)     ((x) & ~(mask))
  18 #define PTR_ALIGN_FLOOR(p, a) \
  19                         ((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
  20
  21 /*
  22  * Align pointer on natural object alignment.
  23  */
  24 #define object_align(obj)       PTR_ALIGN(obj, __alignof__(*(obj)))
  25 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  26
  27 /**
  28  * offset_align - Calculate the offset needed to align an object on its natural
  29  *                alignment towards higher addresses.
  30  * @align_drift:  object offset from an "alignment"-aligned address.
  31  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  32  *
  33  * Returns the offset that must be added to align towards higher
  34  * addresses.
  35  */
  36 #define offset_align(align_drift, alignment)                                   \
  37         ({                                                                     \
  38                 BUILD_RUNTIME_BUG_ON((alignment) == 0                          \
  39                                    || ((alignment) & ((alignment) - 1)));      \
  40                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  41         })
  42
  43 /**
  44  * offset_align_floor - Calculate the offset needed to align an object
  45  *                      on its natural alignment towards lower addresses.
  46  * @align_drift:  object offset from an "alignment"-aligned address.
  47  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  48  *
  49  * Returns the offset that must be substracted to align towards lower addresses.
  50  */
  51 #define offset_align_floor(align_drift, alignment)                             \
  52         ({                                                                     \
  53                 BUILD_RUNTIME_BUG_ON((alignment) == 0                          \
  54                                    || ((alignment) & ((alignment) - 1)));      \
  55                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  56         })
  57
  58 #endif /* __KERNEL__ */
  59
  60 #endif