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Article #6175Re: Assembly question from turnip
From: Kent Paul Dolan
Date: Mon, 29 Oct 1990 20:51
Date: Mon, 29 Oct 1990 20:51
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1529 bytes
lphillips@lpami.wimsey.bc.ca (Larry Phillips) writes: > dfrancis@tronsbox.xei.com (Dennis Francis Heffernan) writes: [...] >> As for checking the condition codes, I was under the impression that >>any time you moved a zero into a data register, the zero flag was set. I >>don't see then how the system calls could NOT set the flag, but I'll take your >>words for it. >There is no guarantee that the last operation to affect the condition codes is >the one you are interested in (the move of the result to D0). In other words, >the result might be moved to D0, then something else moved to or from another >data reg, before control is returned to your program. WHAT? How can you do multitasking at all, if whatever's the 68000's version of the program status register's set of condition flags, isn't restored after a context switch? I guess my ignorance is showing, but this sure isn't how the world used to look the last time I worked at the assembly level. What did I miss? Kent, the man from xanth. <xanthian@Zorch.SF-Bay.ORG> <xanthian@well.sf.ca.us>
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!julius.cs.uiuc.edu!apple!vsi1!zorch!xanthian From: xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) Newsgroups: comp.sys.amiga.tech Subject: Re: Assembly question from turnip Keywords: can allocmem crash? Message-ID: <1990Oct29.205140.28826@zorch.SF-Bay.ORG> Date: 29 Oct 90 20:51:40 GMT References: <2169@lpami.wimsey.bc.ca> Organization: SF-Bay Public-Access Unix Lines: 21