.. mode: -*- rst -*- Ranges of addresses =================== :Tag: design.mps.range :Author: Gareth Rees :Date: 2013-05-21 :Status: complete design :Revision: $Id: //info.ravenbrook.com/project/mps/version/1.116/design/range.txt#1 $ :Copyright: See section `Copyright and License`_. :Index terms: pair: address range; design Introduction ------------ _`.intro`: This is the design of the Range module, which implements objects representing address ranges. _`.readership`: This document is intended for any MPS developer. Requirements ------------ _`.req.range`: A range object must be able to represent an arbitrary range of addresses that neither starts at ``NULL`` nor includes the top grain of the address space. _`.req.empty`: A range object must be able to represent the empty range. _`.req.stack-alloc`: It must be possible to allocate range objects on the stack: that is, they do not require any heap resource. Interface --------- ``typedef RangeStruct *Range`` ``Range`` is the type of a range. It is an alias for ``RangeStruct *``. ``RangeStruct`` is defined in the header so that it can be inlined in client structures or allocated on the stack. Clients must not depend on its implementation details. ``void RangeInit(Range range, Addr base, Addr limit)`` Initialize a range object to represent the half-open address range between ``base`` (inclusive) and ``limit`` (exclusive). It must be the case that ``base <= limit``. If ``base == limit`` then the range is empty. ``void RangeCopy(Range dest, Range src)`` Initialize ``dest`` to be a copy of ``src``. ``void RangeInitSize(Range range, Addr base, Size size)`` Initialize a range object to represent the half-open address range between ``base`` (inclusive) and ``base + size`` (exclusive). If ``size == 0`` then the range is empty. ``void RangeFinish(Range range)`` Finish a range object. Because a range object uses no heap resources (`.req.stack-alloc`_) it is not necessary to call this. However, clients may wish to do so in order to ensure that the range object is invalid. ``Addr RangeBase(Range range)`` Return the base of the range. (This is implemented as a macro, but there is a function too.) ``Addr RangeLimit(Range range)`` Return the limit of the range. (This is implemented as a macro, but there is a function too.) ``Size RangeSize(Range range)`` Return the size of the range. (This is implemented as a macro, but there is a function too. The macro evaluates its argument twice.) ``Bool RangeContains(Range range, Addr addr)`` Return ``TRUE`` if ``addr`` belongs to the range, or ``FALSE`` if it does not. (This is implemented as a macro, but there is a function too. The macro evaluates its arguments twice.) ``Bool RangeIsEmpty(Range range)`` Return ``TRUE`` if the range is empty (contains no addresses), ``FALSE`` otherwise. (This is implemented as a macro, but there is a function too. The macro evaluates its argument twice.) ``Bool RangeIsAligned(Range range, Align alignment)`` Return ``TRUE`` if the base and limit of the range are both aligned to the given alignment, or ``FALSE`` if either is not. ``Bool RangesOverlap(Range range1, Range range2)`` Return ``TRUE`` if the two ranges overlap (have at least one address in common), or ``FALSE`` if they do not. Note that ranges [*A*, *B*) and [*B*, *C*) do not overlap. ``Bool RangesNest(Range outer, Range inner)`` Return ``TRUE`` if all addresses in ``inner`` are also in ``outer``, or ``FALSE`` otherwise. Document history ---------------- - 2013-05-21 GDR_ Created. - 2014-01-15 GDR_ Added ``RangeContains``. .. _GDR: http://www.ravenbrook.com/consultants/gdr/ Copyright and License --------------------- Copyright © 2013-2014 Ravenbrook Limited . All rights reserved. This is an open source license. Contact Ravenbrook for commercial licensing options. 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