src/common/align.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #ifndef _BABELTRACE_ALIGN_H
   8 #define _BABELTRACE_ALIGN_H
   9
  10 #include "compat/compiler.h"
  11 #include "compat/limits.h"
  12
  13 #define BT_ALIGN(x, a)          __BT_ALIGN_MASK(x, (__typeof__(x))(a) - 1)
  14 #define __BT_ALIGN_MASK(x, mask)        (((x) + (mask)) & ~(mask))
  15 #define BT_PTR_ALIGN(p, a)              ((__typeof__(p)) BT_ALIGN((unsigned long) (p), a))
  16 #define BT_ALIGN_FLOOR(x, a)    __BT_ALIGN_FLOOR_MASK(x, (__typeof__(x)) (a) - 1)
  17 #define __BT_ALIGN_FLOOR_MASK(x, mask)  ((x) & ~(mask))
  18 #define BT_PTR_ALIGN_FLOOR(p, a) \
  19                         ((__typeof__(p)) BT_ALIGN_FLOOR((unsigned long) (p), a))
  20 #define BT_IS_ALIGNED(x, a)     (((x) & ((__typeof__(x)) (a) - 1)) == 0)
  21
  22 /*
  23  * Align pointer on natural object alignment.
  24  */
  25 #define bt_object_align(obj)            BT_PTR_ALIGN(obj, __alignof__(*(obj)))
  26 #define bt_object_align_floor(obj)      BT_PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  27
  28 /**
  29  * bt_offset_align - Calculate the offset needed to align an object on its
  30  *                   natural alignment towards higher 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 added to align towards higher
  35  * addresses.
  36  */
  37 #define offset_align(align_drift, alignment)                                   \
  38         ({                                                                     \
  39                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  40                                    || ((alignment) & ((alignment) - 1)));      \
  41                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  42         })
  43
  44 /**
  45  * bt_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 bt_offset_align_floor(align_drift, alignment)                          \
  53         ({                                                                     \
  54                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  55                                    || ((alignment) & ((alignment) - 1)));      \
  56                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  57         })
  58
  59 #endif /* _BABELTRACE_ALIGN_H */