include/ctf/align.h

   1 #ifndef _CTF_ALIGN_H
   2 #define _CTF_ALIGN_H
   3
   4 /*
   5  * align.h - alignment header
   6  *
   7  * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include <ctf/compiler.h>
  25
  26 #define ALIGN(x, a)             __ALIGN_MASK(x, (typeof(x))(a) - 1)
  27 #define __ALIGN_MASK(x, mask)   (((x) + (mask)) & ~(mask))
  28 #define PTR_ALIGN(p, a)         ((typeof(p)) ALIGN((unsigned long) (p), a))
  29 #define ALIGN_FLOOR(x, a)       __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
  30 #define __ALIGN_FLOOR_MASK(x, mask)     ((x) & ~(mask))
  31 #define PTR_ALIGN_FLOOR(p, a) \
  32                         ((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
  33 #define IS_ALIGNED(x, a)        (((x) & ((typeof(x)) (a) - 1)) == 0)
  34
  35 /*
  36  * Align pointer on natural object alignment.
  37  */
  38 #define object_align(obj)       PTR_ALIGN(obj, __alignof__(*(obj)))
  39 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  40
  41 /**
  42  * offset_align - Calculate the offset needed to align an object on its natural
  43  *                alignment towards higher addresses.
  44  * @align_drift:  object offset from an "alignment"-aligned address.
  45  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  46  *
  47  * Returns the offset that must be added to align towards higher
  48  * addresses.
  49  */
  50 #define offset_align(align_drift, alignment)                                   \
  51         ({                                                                     \
  52                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  53                                    || ((alignment) & ((alignment) - 1)));      \
  54                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  55         })
  56
  57 /**
  58  * offset_align_floor - Calculate the offset needed to align an object
  59  *                      on its natural alignment towards lower addresses.
  60  * @align_drift:  object offset from an "alignment"-aligned address.
  61  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  62  *
  63  * Returns the offset that must be substracted to align towards lower addresses.
  64  */
  65 #define offset_align_floor(align_drift, alignment)                             \
  66         ({                                                                     \
  67                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  68                                    || ((alignment) & ((alignment) - 1)));      \
  69                 (((align_drift) - (alignment)) & ((alignment) - 1);            \
  70         })
  71
  72 #endif /* _CTF_ALIGN_H */