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<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Your probably
right. That makes sense.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>It’s certainly easier
to code than using static blocks and reusing them.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif";color:windowtext'>From:</span></b><span lang=EN-US
style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>
delphi-bounces@delphi.org.nz [mailto:delphi-bounces@delphi.org.nz] <b>On Behalf
Of </b>Rohit Gupta<br>
<b>Sent:</b> Friday, 24 September 2010 12:48 PM<br>
<b>To:</b> NZ Borland Developers Group - Delphi List<br>
<b>Subject:</b> Re: [DUG] Memory allocation speed<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I think that because your chunk size is constant, the memory
manager just returns previous blocks to you. So fragmentation does not
occur.<br>
<br>
On 24/09/2010 01:52, Ross Levis wrote: <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Just wanted
some opinions on how bad a practice this is!</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>I have written
a media player which uses a DLL to decode audio files.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>The DLL opens an
MP3 file for example, and sends back decoded raw audio, usually in chunks of
4608 bytes (~20ms), but could be a different size.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>I need to
buffer this audio data for around 5 seconds (1 MB).</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Rather than
writing a complicated circular buffer which feeds in one end and is taken from
the other, I decided to simply allocate memory for each new chunk and store a
link from one memory location to the next. The oldest buffer is read and
memory released.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>So there is
roughly 1 new memory space being allocated and 1 being destroyed every 20ms or
so, with around 200 chunks being stored at any one time.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>I’m using D7
with the FastMM4 memory manager.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>It is working
very well with very little CPU usage at all, which I was surprised at.
I’ve always been under the impression that allocating memory is a slow process.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;color:#1F497D'>Thoughts?</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><br>
<br>
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<o:p></o:p></span></p>
<pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>NZ Borland Developers Group - Delphi mailing list<o:p></o:p></pre><pre>Post: <a
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<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>--
<br>
Regards<br>
<br>
<b>Rohit Gupta</b><br>
B.E. Elec., M.E., Mem IEEE, Member IET<br>
Technical Manager<br>
Computer Fanatics Ltd<br>
<br>
<b>Tel </b>4892280 <br>
<b>Fax </b>4892290 <br>
<b>Web </b>www.cfl.co.nz<o:p></o:p></span></p>
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