align.h: support cygwin page size
[lttng-ust.git] / include / lttng / align.h
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1#ifndef _UST_ALIGN_H
2#define _UST_ALIGN_H
3
4/*
4318ae1b 5 * lttng/align.h
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6 *
7 * (C) Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 *
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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:
a60d70e6 15 *
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16 * The above copyright notice and this permission notice shall be included in
17 * all copies or substantial portions of the Software.
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18 */
19
4318ae1b 20#include <lttng/bug.h>
993e8a49 21#include <unistd.h>
b048179f 22#include <limits.h>
8c4127c5 23
b048179f 24#ifndef PAGE_SIZE /* Cygwin limits.h defines its own PAGE_SIZE */
993e8a49 25#define PAGE_SIZE sysconf(_SC_PAGE_SIZE)
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26#endif
27
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28#define PAGE_MASK (~(PAGE_SIZE - 1))
29#define __ALIGN_MASK(v, mask) (((v) + (mask)) & ~(mask))
2e349edd 30#define ALIGN(v, align) __ALIGN_MASK(v, (__typeof__(v)) (align) - 1)
993e8a49 31#define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)
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32
33/**
34 * offset_align - Calculate the offset needed to align an object on its natural
35 * alignment towards higher addresses.
36 * @align_drift: object offset from an "alignment"-aligned address.
37 * @alignment: natural object alignment. Must be non-zero, power of 2.
38 *
39 * Returns the offset that must be added to align towards higher
40 * addresses.
41 */
42#define offset_align(align_drift, alignment) \
43 ({ \
3f12fcef 44 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0 \
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45 || ((alignment) & ((alignment) - 1))); \
46 (((alignment) - (align_drift)) & ((alignment) - 1)); \
47 })
48
49/**
50 * offset_align_floor - Calculate the offset needed to align an object
51 * on its natural alignment towards lower addresses.
52 * @align_drift: object offset from an "alignment"-aligned address.
53 * @alignment: natural object alignment. Must be non-zero, power of 2.
54 *
55 * Returns the offset that must be substracted to align towards lower addresses.
56 */
57#define offset_align_floor(align_drift, alignment) \
58 ({ \
3f12fcef 59 LTTNG_BUILD_RUNTIME_BUG_ON((alignment) == 0 \
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60 || ((alignment) & ((alignment) - 1))); \
61 (((align_drift) - (alignment)) & ((alignment) - 1); \
62 })
63
64#endif /* _UST_ALIGN_H */
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