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Newsgroups: | comp.os.msdos.djgpp |
From: | Peter Berdeklis <peter AT atmosp DOT physics DOT utoronto DOT ca> |
Subject: | Re: 32 bit registers |
Message-ID: | <Pine.SGI.3.91.961227091018.11029A-100000@chinook.physics.utoronto.ca> |
Nntp-Posting-Host: | chinook.physics.utoronto.ca |
Sender: | news AT info DOT physics DOT utoronto DOT ca (System Administrator) |
Mime-Version: | 1.0 |
Organization: | University of Toronto - Dept. of Physics |
In-Reply-To: | <59vm0n$7gu$1@troll.powertech.no> |
Date: | Fri, 27 Dec 1996 14:11:56 GMT |
References: | <59cs4f$58k AT nr1 DOT ottawa DOT istar DOT net> <19961224 DOT 142048 DOT 4751 DOT 1 DOT chambersb AT juno DOT com> <59t1qo$tv0$1 AT troll DOT powertech DOT no> <Pine DOT SGI DOT 3 DOT 91 DOT 961226120517 DOT 2924F-100000 AT chinook DOT physics DOT utoronto DOT ca> <59vm0n$7gu$1 AT troll DOT powertech DOT no> |
Lines: | 27 |
To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
On Thu, 26 Dec 1996, Ove Kaaven wrote: > Peter Berdeklis <peter AT atmosp DOT physics DOT utoronto DOT ca> wrote: > > >On Thu, 26 Dec 1996, Ove Kaaven wrote: > >> To load the 16-bit value in bx into the high-order word of eax and > >> preserving everything else, you could try: > >> > >> roll $16,%eax > >> movw %bx,%ax > >> roll $16,%eax > > ^^^ should be $17 > > >roll moves the last bit into the carry flag, so you have to roll one more > >bit (the last time only) to get the bit out of the carry flag and into > >the MSB of the register. > > Really? I thought that was the behaviour of rcl, not rol, hmm... Forgive me, I misread my reference. rol _copies_ the last bit rotated into the carry flag, it doesn't shift through it as does rcl. It's all getting so blurry! :) --------------- Peter Berdeklis Dept. of Physics, Univ. of Toronto
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