Date: Sun, 8 Mar 1998 13:34:20 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Vincenzo Morello <morellov AT tin DOT it>
cc: djgpp AT delorie DOT com
Subject: Re: _bios_disk() inefficiency
In-Reply-To: <34FDC92D.23D8@tin.it>
Message-ID: <Pine.SUN.3.91.980308133407.22686H-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Precedence: bulk


On Wed, 4 Mar 1998, Vincenzo Morello wrote:

> I get very low performance in a DJGPP V2 program which has to read large
> disk data in low level mode.
> I use _bios_disk() to read the disk and the program runs *five times*
> slower than in Borland real mode.

You don't tell much about your program, so it's hard to give any smart
advice.  Theoretically, you could make a DJGPP version 1000 times
slower if you, for example, called the BIOS for every byte you needed
to read.  Calling BIOS requires a mode switch which is slow, so you
should make as few calls as you can.  In particular, reading more of
the disk at a time and then working on data in memory should speed
your program a lot.  In DJGPP, you could even read an entire diskette
into memory in one swell whoop.