src/common/align.h

   1 #ifndef _BABELTRACE_ALIGN_H
   2 #define _BABELTRACE_ALIGN_H
   3
   4 /*
   5  * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23  * SOFTWARE.
  24  */
  25
  26 #include "compat/compiler.h"
  27 #include "compat/limits.h"
  28
  29 #define ALIGN(x, a)             __ALIGN_MASK(x, (typeof(x))(a) - 1)
  30 #define __ALIGN_MASK(x, mask)   (((x) + (mask)) & ~(mask))
  31 #define PTR_ALIGN(p, a)         ((typeof(p)) ALIGN((unsigned long) (p), a))
  32 #define ALIGN_FLOOR(x, a)       __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
  33 #define __ALIGN_FLOOR_MASK(x, mask)     ((x) & ~(mask))
  34 #define PTR_ALIGN_FLOOR(p, a) \
  35                         ((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
  36 #define IS_ALIGNED(x, a)        (((x) & ((typeof(x)) (a) - 1)) == 0)
  37
  38 /*
  39  * Align pointer on natural object alignment.
  40  */
  41 #define object_align(obj)       PTR_ALIGN(obj, __alignof__(*(obj)))
  42 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  43
  44 /**
  45  * offset_align - Calculate the offset needed to align an object on its natural
  46  *                alignment towards higher 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 added to align towards higher
  51  * addresses.
  52  */
  53 #define offset_align(align_drift, alignment)                                   \
  54         ({                                                                     \
  55                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  56                                    || ((alignment) & ((alignment) - 1)));      \
  57                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  58         })
  59
  60 /**
  61  * offset_align_floor - Calculate the offset needed to align an object
  62  *                      on its natural alignment towards lower addresses.
  63  * @align_drift:  object offset from an "alignment"-aligned address.
  64  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  65  *
  66  * Returns the offset that must be substracted to align towards lower addresses.
  67  */
  68 #define offset_align_floor(align_drift, alignment)                             \
  69         ({                                                                     \
  70                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  71                                    || ((alignment) & ((alignment) - 1)));      \
  72                 (((align_drift) - (alignment)) & ((alignment) - 1));           \
  73         })
  74
  75 #endif /* _BABELTRACE_ALIGN_H */