include/lttng/align.h

   1 #ifndef _UST_ALIGN_H
   2 #define _UST_ALIGN_H
   3
   4 /*
   5  * lttng/align.h
   6  *
   7  * (C) Copyright 2010-2011 - 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 <lttng/bug.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 PAGE_MASK               (~(PAGE_SIZE - 1))
  37 #define __ALIGN_MASK(v, mask)   (((v) + (mask)) & ~(mask))
  38 #define ALIGN(v, align)         __ALIGN_MASK(v, (__typeof__(v)) (align) - 1)
  39 #define PAGE_ALIGN(addr)        ALIGN(addr, PAGE_SIZE)
  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                 LTTNG_BUILD_RUNTIME_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                 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0                    \
  68                                    || ((alignment) & ((alignment) - 1)));      \
  69                 (((align_drift) - (alignment)) & ((alignment) - 1);            \
  70         })
  71
  72 #endif /* _UST_ALIGN_H */