Date: Sun, 28 Oct 2001 10:50:29 -0500 From: Sergey Babkin <babkin@bellatlantic.net> To: Matthew Emmerton <matt@gsicomp.on.ca> Cc: hackers@freebsd.org Subject: Re: Simple x86 assembler question Message-ID: <3BDC2945.42972E63@bellatlantic.net> References: <003901c15f3c$5bdef760$1200a8c0@gsicomp.on.ca>
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Matthew Emmerton wrote: > > Hi all, > > This weekend I decided to do some assembly hacking on some object-only code > that I've lost the C source for. Since I haven't coded assembler for at > least 8 years, and I threw my x86 assembly manuals out when I moved 6 months > ago, there are a few things that are stumping me. > > In particular, am I interpreting these instructions correctly? > > 0x80839fb <uttstrbyt+43>: movzbl (%edx,%eax,1),%eax > > Takes %eax + %edx, obtains the byte value in memory at that address, > zero-extends and places into %eax Correct. > 0x80839ff <uttstrbyt+47>: movzwl 0xe90(%ebx,%eax,2),%edx > > Takes %eax + %ebx + 0xe90, obtains the word value in memory at that address, > zero-extends and places in %edx. Here the correct address is %eax*2 + %ebx + 0xe90 -SB To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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