include/babeltrace/align.h

   1 #ifndef _BABELTRACE_ALIGN_H
   2 #define _BABELTRACE_ALIGN_H
   3
   4 /*
   5  * BabelTrace align.h - alignment header
   6  *
   7  * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  */
  19
  20 #include <babeltrace/compiler.h>
  21 #include <unistd.h>
  22 #include <limits.h>
  23
  24 #ifndef PAGE_SIZE               /* Cygwin limits.h defines its own PAGE_SIZE */
  25 #define PAGE_SIZE               sysconf(_SC_PAGE_SIZE)
  26 #endif
  27
  28 #define ALIGN(x, a)             __ALIGN_MASK(x, (typeof(x))(a) - 1)
  29 #define __ALIGN_MASK(x, mask)   (((x) + (mask)) & ~(mask))
  30 #define PTR_ALIGN(p, a)         ((typeof(p)) ALIGN((unsigned long) (p), a))
  31 #define ALIGN_FLOOR(x, a)       __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
  32 #define __ALIGN_FLOOR_MASK(x, mask)     ((x) & ~(mask))
  33 #define PTR_ALIGN_FLOOR(p, a) \
  34                         ((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
  35 #define IS_ALIGNED(x, a)        (((x) & ((typeof(x)) (a) - 1)) == 0)
  36
  37 /*
  38  * Align pointer on natural object alignment.
  39  */
  40 #define object_align(obj)       PTR_ALIGN(obj, __alignof__(*(obj)))
  41 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  42
  43 /**
  44  * offset_align - Calculate the offset needed to align an object on its natural
  45  *                alignment towards higher 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 added to align towards higher
  50  * addresses.
  51  */
  52 #define offset_align(align_drift, alignment)                                   \
  53         ({                                                                     \
  54                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  55                                    || ((alignment) & ((alignment) - 1)));      \
  56                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  57         })
  58
  59 /**
  60  * offset_align_floor - Calculate the offset needed to align an object
  61  *                      on its natural alignment towards lower addresses.
  62  * @align_drift:  object offset from an "alignment"-aligned address.
  63  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  64  *
  65  * Returns the offset that must be substracted to align towards lower addresses.
  66  */
  67 #define offset_align_floor(align_drift, alignment)                             \
  68         ({                                                                     \
  69                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  70                                    || ((alignment) & ((alignment) - 1)));      \
  71                 (((align_drift) - (alignment)) & ((alignment) - 1);            \
  72         })
  73
  74 #endif /* _BABELTRACE_ALIGN_H */