Misc/abrash-black-book
Watch
1
0
Fork
You've already forked abrash-black-book
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Retidy, removing align=left from headings and empty paragraphs

Browse source
This commit is contained in:
James Gregory 2013-12-30 15:37:13 +11:00
commit a96a114403
362 changed files with 8472 additions and 5040 deletions
Download patch file Download diff file Expand all files Collapse all files

31
09-03.html
View file

@ -1,5 +1,4 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
@ -19,17 +18,21 @@
<center>
<table border="1">
<tr>
<td><a href="09-02.html">Previous</a></td>
<td>
<a href="09-02.html">Previous</a>
</td>
<td><a href="index.html">Table of Contents</a></td>
<td>
<a href="index.html">Table of Contents</a>
</td>
<td><a href="09-04.html">Next</a></td>
<td>
<a href="09-04.html">Next</a>
</td>
</tr>
</table>
</center>
<p><br /></p>
<p>Listing 9.1 implements the scan-on-first-character approach. Listing 9.2 scans for whatever character the caller specifies. Listing 9.3 is a test program used to compare the two approaches. How much difference does Rob&rsquo;s revelation make? Plenty. Even when the entire C function call to <b>FindString</b> is timed&mdash;<b>strlen</b> calls, parameter pushing, calling, setup, and all&mdash;the version of <b>FindString</b> in Listing 9.2, which is directed by Listing 9.3 to scan for the infrequently-occurring &ldquo;Q,&rdquo; is about 40 percent faster on a 20 MHz cached 386 for the test search of Listing 9.3 than is the version of <b>FindString</b> in Listing 9.1, which always scans for the first character, in this case &ldquo;E.&rdquo; However, when only the search loops (the code that actually does the searching) in the two versions of <b>FindString</b> are compared, Listing 9.2 is more than <i>twice</i> as fast as Listing 9.1&mdash;a remarkable improvement over code that already uses <b>REPNZ SCASB</b> and <b>REPZ CMPS</b>.</p>
<p>What I like so much about Rob&rsquo;s approach is that it demonstrates that optimization involves much more than instruction selection and cycle counting. Listings 9.1 and 9.2 use pretty much the same instructions, and even use the same approach of scanning with <b>REPNZ SCASB</b> and using <b>REPZ CMPS</b> to check scanning matches.</p>
@ -140,16 +143,20 @@ _FindStringendp
end
</pre>
<p><br /></p>
<center>
<table border="1">
<tr>
<td><a href="09-02.html">Previous</a></td>
<td>
<a href="09-02.html">Previous</a>
</td>
<td><a href="index.html">Table of Contents</a></td>
<td>
<a href="index.html">Table of Contents</a>
</td>
<td><a href="09-04.html">Next</a></td>
<td>
<a href="09-04.html">Next</a>
</td>
</tr>
</table>
</center>