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  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  25  * SOFTWARE.
  26  */
  27
  28 #include <babeltrace/compiler.h>
  29 #include <unistd.h>
  30 #include <limits.h>
  31
  32 #ifndef PAGE_SIZE               /* Cygwin limits.h defines its own PAGE_SIZE */
  33 #define PAGE_SIZE               sysconf(_SC_PAGE_SIZE)
  34 #endif
  35
  36 #define ALIGN(x, a)             __ALIGN_MASK(x, (typeof(x))(a) - 1)
  37 #define __ALIGN_MASK(x, mask)   (((x) + (mask)) & ~(mask))
  38 #define PTR_ALIGN(p, a)         ((typeof(p)) ALIGN((unsigned long) (p), a))
  39 #define ALIGN_FLOOR(x, a)       __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
  40 #define __ALIGN_FLOOR_MASK(x, mask)     ((x) & ~(mask))
  41 #define PTR_ALIGN_FLOOR(p, a) \
  42                         ((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
  43 #define IS_ALIGNED(x, a)        (((x) & ((typeof(x)) (a) - 1)) == 0)
  44
  45 /*
  46  * Align pointer on natural object alignment.
  47  */
  48 #define object_align(obj)       PTR_ALIGN(obj, __alignof__(*(obj)))
  49 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
  50
  51 /**
  52  * offset_align - Calculate the offset needed to align an object on its natural
  53  *                alignment towards higher addresses.
  54  * @align_drift:  object offset from an "alignment"-aligned address.
  55  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  56  *
  57  * Returns the offset that must be added to align towards higher
  58  * addresses.
  59  */
  60 #define offset_align(align_drift, alignment)                                   \
  61         ({                                                                     \
  62                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  63                                    || ((alignment) & ((alignment) - 1)));      \
  64                 (((alignment) - (align_drift)) & ((alignment) - 1));           \
  65         })
  66
  67 /**
  68  * offset_align_floor - Calculate the offset needed to align an object
  69  *                      on its natural alignment towards lower addresses.
  70  * @align_drift:  object offset from an "alignment"-aligned address.
  71  * @alignment:    natural object alignment. Must be non-zero, power of 2.
  72  *
  73  * Returns the offset that must be substracted to align towards lower addresses.
  74  */
  75 #define offset_align_floor(align_drift, alignment)                             \
  76         ({                                                                     \
  77                 MAYBE_BUILD_BUG_ON((alignment) == 0                            \
  78                                    || ((alignment) & ((alignment) - 1)));      \
  79                 (((align_drift) - (alignment)) & ((alignment) - 1);            \
  80         })
  81
  82 #endif /* _BABELTRACE_ALIGN_H */