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From: | "Tom St Denis" <tomstdenis AT yahoo DOT com> |
Newsgroups: | comp.os.msdos.djgpp |
References: | <3a9e955b DOT 2750392 AT news DOT redshift DOT com> |
Subject: | Re: Using DMA for hard disk access? |
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Message-ID: | <RqAn6.42$c7.131162@news3.rdc1.on.home.com> |
Date: | Thu, 01 Mar 2001 22:54:41 GMT |
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To: | djgpp AT delorie DOT com |
DJ-Gateway: | from newsgroup comp.os.msdos.djgpp |
Reply-To: | djgpp AT delorie DOT com |
"Damon Casale" <damon AT redshift DOT com> wrote in message news:3a9e955b DOT 2750392 AT news DOT redshift DOT com... > I'm trying to squeeze the last ounce of speed out of this compression > program, and I'm wondering if switching to direct DMA calls, as > opposed to using the INT13h or INT21h disk read-write calls, would > help things much. As far as programming in DJGPP goes, I know that it > takes a lot of CPU cycles to switch from protected mode to real mode, > and then back again, to make the interrupt calls. Would I avoid that > by doing DMA calls instead? > > Has anyone tried something like this? If so, do you have any advice? > I'm not entirely sure how to tell the hard drive what sectors I want > to read or write, but I _think_ I know how to use the DMA I/O ports. > Where would I look for more detailed info on this? Advice? Um... oh I don't know... um DONT DO IT. There is a reason int 21h exists... and it ain't to make things slow. Tom
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