projects / lttng-modules.git / blame
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1 | #ifndef _LTTNG_ALIGN_H |
| 2 | #define _LTTNG_ALIGN_H | |
| 3 | ||
| 4 | /* | |
| 5 | * lib/align.h | |
| 6 | * | |
| 886d51a3 | 7 | * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 6c29ebe7 | 8 | * |
| 886d51a3 MD |
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; only | |
| 12 | * version 2.1 of the License. | |
| 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 | |
| 6c29ebe7 MD |
22 | */ |
| 23 | ||
| 24 | #ifdef __KERNEL__ | |
| 25 | ||
| 26 | #include <linux/types.h> | |
| 5671a661 | 27 | #include <lib/bug.h> |
| 6c29ebe7 MD |
28 | |
| 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 | ||
| 34 | /* | |
| 35 | * Align pointer on natural object alignment. | |
| 36 | */ | |
| 37 | #define object_align(obj) PTR_ALIGN(obj, __alignof__(*(obj))) | |
| 38 | #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj))) | |
| 39 | ||
| 40 | /** | |
| 41 | * offset_align - Calculate the offset needed to align an object on its natural | |
| 42 | * alignment towards higher addresses. | |
| 43 | * @align_drift: object offset from an "alignment"-aligned address. | |
| 44 | * @alignment: natural object alignment. Must be non-zero, power of 2. | |
| 45 | * | |
| 46 | * Returns the offset that must be added to align towards higher | |
| 47 | * addresses. | |
| 48 | */ | |
| 49 | #define offset_align(align_drift, alignment) \ | |
| 50 | ({ \ | |
| 51 | BUILD_RUNTIME_BUG_ON((alignment) == 0 \ | |
| 52 | || ((alignment) & ((alignment) - 1))); \ | |
| 53 | (((alignment) - (align_drift)) & ((alignment) - 1)); \ | |
| 54 | }) | |
| 55 | ||
| 56 | /** | |
| 57 | * offset_align_floor - Calculate the offset needed to align an object | |
| 58 | * on its natural alignment towards lower addresses. | |
| 59 | * @align_drift: object offset from an "alignment"-aligned address. | |
| 60 | * @alignment: natural object alignment. Must be non-zero, power of 2. | |
| 61 | * | |
| 62 | * Returns the offset that must be substracted to align towards lower addresses. | |
| 63 | */ | |
| 64 | #define offset_align_floor(align_drift, alignment) \ | |
| 65 | ({ \ | |
| 66 | BUILD_RUNTIME_BUG_ON((alignment) == 0 \ | |
| 67 | || ((alignment) & ((alignment) - 1))); \ | |
| e860f019 | 68 | (((align_drift) - (alignment)) & ((alignment) - 1)); \ |
| 6c29ebe7 MD |
69 | }) |
| 70 | ||
| 71 | #endif /* __KERNEL__ */ | |
| 72 | ||
| 73 | #endif |