Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!pilchuck!amc-gw!sumax!ole!ray
From: ray@ole.UUCP (Ray Berry)
Newsgroups: comp.sys.ibm.pc
Subject: 386: looping with ecx
Keywords: ASM 386
Message-ID: <864@ole.UUCP>
Date: 28 Jun 89 22:11:47 GMT
Distribution: na
Organization: Seattle Silicon Corp., Bellevue, WA.
Lines: 13


	I'm trying to write an ASM function for the 386 to execute in the
pc environment in which register ecx is used as a loop counter - the count
explicitly being greater than 2^16.  386 asm references I've looked at say
that the loop instruction DOES use ecx.  However, when I execute the func-
tion, the top half of ecx is ignored and the loop terminates prematurely.
	I'm suspicious that the operating mode of the cpu has something
to do with this, and/or that ecx can be enabled explicitly by using the
'OPSIZ' prefix... Does anyone have a grip on this?  Does masm support 
this prefix?  TASM?
-- 
Ray Berry  KB7HT uucp: ...{sumax|thebes|quick}!ole!ray     CIS 73407,3152
Seattle Silicon Corp. 3075 112th Ave NE. Bellevue WA 98004 (206) 828 4422