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| From: | "John S. Fine" <johnfine AT erols DOT com> |
| Newsgroups: | comp.os.msdos.djgpp |
| Subject: | Re: Some assembly questions |
| Date: | Thu, 18 Mar 1999 17:00:10 -0500 |
| Lines: | 18 |
| Message-ID: | <36F1776A.6DA0@erols.com> |
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| NNTP-Posting-Date: | 18 Mar 1999 22:01:34 GMT |
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| To: | djgpp AT delorie DOT com |
| DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
| Reply-To: | djgpp AT delorie DOT com |
Martin Str|mberg wrote: > Perhaps somebody can inform me on the difference (if there is one) > between "cmpl $1, %eax" and "testl $1, %eax". CMP internally does a SUB, discarding the result and keeping only the condition codes from the result. TEST internally does an AND, discarding the result and keeping only the condition codes from the result. Since SUB is very different from AND, CMP is very different from TEST. For example, cmpl $1 will set the Z-bit only if the entire target is equal to one. testl $1 will set the Z-bit if the target is any even number. -- http://www.erols.com/johnfine/ http://www.geocities.com/SiliconValley/Peaks/8600/
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