From 8c4127c54bd88217088e231cf197d9b81d15e13a Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 16 Jun 2011 15:33:48 -0400 Subject: [PATCH] Add alignment header Signed-off-by: Mathieu Desnoyers --- include/ust/align.h | 51 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 include/ust/align.h diff --git a/include/ust/align.h b/include/ust/align.h new file mode 100644 index 0000000..cd713cc --- /dev/null +++ b/include/ust/align.h @@ -0,0 +1,51 @@ +#ifndef _UST_ALIGN_H +#define _UST_ALIGN_H + +/* + * ust/align.h + * + * (C) Copyright 2010-2011 - Mathieu Desnoyers + * + * Dual LGPL v2.1/GPL v2 license. + */ + +#include + +/* + * Align pointer on natural object alignment. + */ +#define object_align(obj) PTR_ALIGN(obj, __alignof__(*(obj))) +#define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj))) + +/** + * offset_align - Calculate the offset needed to align an object on its natural + * alignment towards higher addresses. + * @align_drift: object offset from an "alignment"-aligned address. + * @alignment: natural object alignment. Must be non-zero, power of 2. + * + * Returns the offset that must be added to align towards higher + * addresses. + */ +#define offset_align(align_drift, alignment) \ + ({ \ + BUILD_RUNTIME_BUG_ON((alignment) == 0 \ + || ((alignment) & ((alignment) - 1))); \ + (((alignment) - (align_drift)) & ((alignment) - 1)); \ + }) + +/** + * offset_align_floor - Calculate the offset needed to align an object + * on its natural alignment towards lower addresses. + * @align_drift: object offset from an "alignment"-aligned address. + * @alignment: natural object alignment. Must be non-zero, power of 2. + * + * Returns the offset that must be substracted to align towards lower addresses. + */ +#define offset_align_floor(align_drift, alignment) \ + ({ \ + BUILD_RUNTIME_BUG_ON((alignment) == 0 \ + || ((alignment) & ((alignment) - 1))); \ + (((align_drift) - (alignment)) & ((alignment) - 1); \ + }) + +#endif /* _UST_ALIGN_H */ -- 2.34.1