From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,ff1c4510e0f5bb8d X-Google-Attributes: gid103376,public From: "David C. Hoos, Sr." Subject: Re: help needed, ada project Date: 1999/01/28 Message-ID: <78popl$gpk@hobbes.crc.com>#1/1 X-Deja-AN: 437932730 References: <36b0501a.0@interalpha.net> X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Organization: Coleman Research Corporation Newsgroups: comp.lang.ada Date: 1999-01-28T00:00:00+00:00 List-Id: michaelb wrote in message <36b0501a.0@interalpha.net>... >hello my name is mike and am in desperate need for some help >I am currently on a BTEC HND in computing and I have a peice of >coursework that is in jeopardy as i have no understanding of the direct_io >file format, could somebody send me some basic examples of this so >that I can complete my course work, > >michaelb@interalpha.co.uk > >any help would be most appreciated. > >p.s. the ada development environment i am using is ada95, i dont >think that there any major differances between this and vax ada. > Instantiations of both Direct_IO and Sequential_IO read and write raw binary files consisting of some quantity of records of the memory images of the type with which they were instantiated. Although I am unaware of any requirements for a specific file format, all of the implementations for which I have examined the files have nothing to delimit the records -- i.e., there are just repetirions of the memory images of the data items which were written. Thus, these files can only be read by a program compiled with a compiler which lays out the type in memory the same way -- whether by default, or by having written the programs with representation clauses on the types which force a particular layout. In practice, this usually means reading and writing on the same platform type, using programs compiled by the same compiler. The only difference between Sequential_IO and Direct_IO, is that Direct_IO allows reading and writing with random access -- i.e., by specifying the record number to read or write, while Sequential_IO is just that -- sequential. I hope this helps. Davis C. Hoos, Sr.