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<FONT COLOR="#AOAO99">Memory API Wrappers</FONT></H3></CENTER>

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<p>This article was contributed by <A HREF="mailto:Poul@wizsoft.com">Poul Costinsky</A>. You can also
find this and other articles at his web site at <A HREF="http://www.wizsoft.com/%7epoul/srs/">http://www.wizsoft.com/~poul/srs/</A>

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        <li><b>One size private heap</b> class&nbsp;<a name="CWizOneSizeHeap"></a>CWizOneSizeHeap.<br>
          I wrote this class for very common situation: when you have to allocate <br>
          many of small objects of the same size; the obvious case is some class widely used in a
          program. The assumption that all objects on the heap are of the same size allows to
          minimize allocation overhead to <b>zero</b>. Indeed, every allocation block in the regular
          heap is preceded by block size. But when the size is known in advance, you could save this
          place. The <b>technique</b> is simple: the heap manager requests big blocks of the memory
          from some common heap. Every block of memory is either occupied by allocated <br>
          object, or points to the next free block. Therefore it manages &quot;in place&quot; linked
          list of free items without any overhead. The sources are <a href="OneSizeHeap.h.htm" tppabs="http://www.codeguru.com/misc/OneSizeHeap.h">here</a>.
          <br>
          <i><u>NB:</u></i> Feel free to <i>remove inlines</i> if you're more concerned about <i>size</i>
          then about <i>speed</i>. <br>
          &nbsp; </li>
        <li><small><font size="+0"><b>Local heap</b> class CWizLocalHeap - wrapper for Win32 API
          local heap machinery.</font><br>
          <font size="+0">Helper class CWizLocalHeapLock useful for locking the heap in the
          multithreading environment.</font> <br>
          <font size="+0">Files <a href="LOCALHEP.H" tppabs="http://www.codeguru.com/misc/LOCALHEP.H">LOCALHEP.H</a> and <a href="LOCALHEP.CPP" tppabs="http://www.codeguru.com/misc/LOCALHEP.CPP">LOCALHEP.CPP</a>
          .</font> </small></li>
        <li><small><font size="+0">Template class CWizTypedLocalHeap derived from CWizLocalHeap to
          avoid mess with local heap parameters.</font><br>
          <font size="+0">Class&nbsp;<a name="CWizDefaultTypedLocalHeap"></a>CWizDefaultTypedLocalHeap
          derived from CWizTypedLocalHeap and supplies reasonable default parameters.</font> <br>
          <font size="+0">Define <b>DECLARE_LOCAL_HEAP</b> forces objects of any class to be
          allocated from it's own private local heap. Very useful in <i>new-intensive</i>
          algorithms.</font> <br>
          Files <a href="TypedLocalHeap.CPP" tppabs="http://www.codeguru.com/misc/TypedLocalHeap.CPP">TypedLocalHeap.CPP</a> and <a href="TypedLocalHeap.H.htm" tppabs="http://www.codeguru.com/misc/TypedLocalHeap.H">TypedLocalHeap.H</a>
          . </small></li>
        <li><small><font size="+0"><b>Virtual memory</b> class&nbsp;<a name="CWizVirtualMemory"></a>CWizVirtualMemory
          - wrapper for Win32 API virtual memory machinery.</font><br>
          <font size="+0">Derived template class CWizTypedVMem to be used as virtual array.</font> <br>
          <font size="+0">Files <a href="VIRT_MEM.H" tppabs="http://www.codeguru.com/misc/VIRT_MEM.H">VIRT_MEM.H</a> and <a href="VIRT_MEM.CPP" tppabs="http://www.codeguru.com/misc/VIRT_MEM.CPP">VIRT_MEM.CPP</a>
          .</font> </small></li>
        <li><b>Memory&nbsp;<a name="memmapfile"></a>mapped file wrappers</b>:</li>
        <ul>
          <li><a name="CWizFileMapping"></a>CWizFileMapping - kind of file mapping wrapper.</li>
          <li><a name="CWizFileMapView"></a>CWizFileMapView - view of this mapping (actual memory
            address).</li>
          <li>template &lt;class TYPE&gt; class CWizFileView - kind of &quot;virtual array&quot;
            mirroring a file.</li>
          <li>template &lt;class TYPE&gt; class CWizROFileView - read-only view (virtual array) of an
            existing file.</li>
          <li>CWizFullFileView - read/write file mapping. Uses CWizTempFileStrategy for managing
            temporary files.</li>
          <li>template &lt;class TYPE&gt; class CWizTypedFullFileView - typed derivative of
            CWizFullFileView.</li>
        </ul>
        <font size="+0"><p>Files <a href="FILE_MAP.H" tppabs="http://www.codeguru.com/misc/FILE_MAP.H">FILE_MAP.H</a> and <a href="FILE_MAP.CPP" tppabs="http://www.codeguru.com/misc/FILE_MAP.CPP">FILE_MAP.CPP</a>
        .</font> <ul>
          <li><a name="CWizFileROFileMapping"></a>CWizFileROFileMapping - implements
            &quot;windowed&quot; view to memory mapping.Useful when address space is low or when
            access to the file is rare. <br>
            Nested class Window acts like actual window to the mapping and moves itself by demand. <br>
            This class has template parameter LOCKER which implements <b>multithreading </b>synchronization
            for Window objects. Two classes supplied for this: </li>
          <li>CWizFileMapNoLocker - no locking and synchronization. Useful when:<p><b>a) </b>only
            single thread accesses the view or <br>
            <b>b)</b> another synchronization implemented in your application or <br>
            <b>c)</b> you are absolutely sure it's no need for synchronization. </p>
          </li>
          <li>CWizFileMapCritSectLocker - uses <b>critical section</b> for synchronization between
            threads.<p><b><u>Please note</u></b> that synchronization is managed only when retrieving
            the view from memory mapping. Every view supposed to be thread-specific or at protected by
            another way. </p>
          </li>
          <li>template&lt;class LOCKER, class DATA&gt; class CWizTypedFileROFileMapping -<br>
            typed derivative of CWizFileROFileMapping (like virtual array of <tt>structs</tt>). <br>
            Because of strange compilation errors -:) the nested class is called Wnd instead of
            Window.</li>
        </ul>
        <font size="+0"><p>Files <a href="FileMapWindow.H.htm" tppabs="http://www.codeguru.com/misc/FileMapWindow.H">FileMapWindow.H</a> and <a
        href="FileMapWindow.CPP.htm" tppabs="http://www.codeguru.com/misc/FileMapWindow.CPP">FileMapWindow.CPP</a> .</font></p>


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