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From: Mark & Zurima McKinney <mckmark@us.net>
Subject: Re: CRC in Ada?
Date: 1997/03/22
Message-ID: <33344C9C.542F@us.net>#1/1
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References: <1997Mar2.220652@nova.wright.edu>
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Organization: US Net - MD,DC,VA ISP - info@us.net
Newsgroups: comp.lang.ada
Date: 1997-03-22T00:00:00+00:00
List-Id: <comp.lang.ada>


Michael Hartsough Wrote

>It should not take 20 minutes to read an 8mb file on a 166MHz pentium >PC.
>Even if one IS "misusing" sequential_io!

I agree. I have worked with several implementations of Ada on several
computers. I've run across the same problem. What you're dealing with is
a correct but inefficient implementation of sequential_io. In one case I
had access to the source of sequential_io, copied it, renamed the
package buffered_sequential_io added buffering and used it. Later I
ported that sytem to another machine using an Alsys product that allowed
the programmer to pass buffering information in the form parameter. 

....
   package Char_io is new Sequential_io (Character);
....
   Char_Io.Create(Char_File, Char_io.In_File, "Filename", "Buffer_Size
=> 4096");
   -- On Alsys this also works for text_io a lager buffer size will
probable improve performance

Not completely portable but extreemly effective. We had a 300 MB file
that could be read in 1 minute vs the C compiler in 2 Min. Using the
Alsys PC compiler I could read the same file in approximatly 6 Minutes
using a 90 mz pentium. 

IMHO Stream_Io may be more appropriate if available. If not
sequential_io is a logical choice unfortunately you have a correct but
inefficient implementation to use.

 
Mark McKinney