Thread View: borland.public.delphi.basm
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Started by chris jones
Fri, 13 Sep 2002 14:41
question about 'rep movsd'
Author: chris jones
Date: Fri, 13 Sep 2002 14:41
Date: Fri, 13 Sep 2002 14:41
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Do i need to check ecx > 0 before using 'rep movsd', or does it just do nothing when ecx <= 0. thanks, chris
Re: question about 'rep movsd'
Author: Per Larsen
Date: Fri, 13 Sep 2002 15:16
Date: Fri, 13 Sep 2002 15:16
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If ECX is exactly zero, rep movsd does nothing. It treats the content of ECX as an unsigned value, however, so if it's really a negative integer you'll get a *lot* of data moved<g>. - Per "chris jones" <flak@clara.co.uk> wrote in message news:3d81f93f$1@newsgroups.borland.com... > Do i need to check ecx > 0 before using 'rep movsd', or does it just do > nothing when ecx <= 0. > > thanks, > > chris > >
Re: question about 'rep movsd'
Author: Pierre Maurette
Date: Sun, 15 Sep 2002 18:25
Date: Sun, 15 Sep 2002 18:25
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"Per Larsen" <perl_NOSPAM@turbopower.com> a �crit dans le message de news: 3d8201b5$1@newsgroups.borland.com... > If ECX is exactly zero, rep movsd does nothing. > It treats the content of ECX as an unsigned value, however, so if it's > really a negative integer you'll get a *lot* of data moved<g>. I was not sure for REP (but you are right). But for LOOP, when ECX is zero, you iniate a very very big loop ! (the whole turn on 32 bits). For this, you have JECXZ and JCXZ instructions. Pierre
Re: question about 'rep movsd'
Author: Pierre Maurette
Date: Sun, 15 Sep 2002 18:25
Date: Sun, 15 Sep 2002 18:25
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"Per Larsen" <perl_NOSPAM@turbopower.com> a �crit dans le message de news: 3d8201b5$1@newsgroups.borland.com... > If ECX is exactly zero, rep movsd does nothing. > It treats the content of ECX as an unsigned value, however, so if it's > really a negative integer you'll get a *lot* of data moved<g>. I was not sure for REP (but you are right). But for LOOP, when ECX is zero, you iniate a very very big loop ! (the whole turn on 32 bits). For this, you have JECXZ and JCXZ instructions. Pierre
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