From: "Nick Roberts" <Nick.Roberts@dial.pipex.com>
Subject: Re: question re Ada equivalent of C function
Date: 1998/02/22
Date: 1998-02-22T00:00:00+00:00 [thread overview]
Message-ID: <01bd3f2d$0b86be20$LocalHost@xhv46.dial.pipex.com> (raw)
In-Reply-To: 6cnj5d$bjq$1@usenet.rational.com
Again, this kind of technique is specific to those architectures with
memory-mapped ports, and even so, there could well be further ramifications
(e.g. access rights, interference, etc.).
It also assumes that an access value is the same as an address: this is not
always so! For fooling around in memory, you're better off using the
facilities provided by the standard packages System.Storage_Elements (RM
13.7.1) and System.Address_To_Access_Conversions (RM 13.7.2).
(I always think it's slightly biblical, quoting chapter-and-verse like that
;-)
== Nick Roberts ================================================
== Croydon, UK ===========================
== ================
== Proprietor, ThoughtWing Software ==========
== Independent Software Development Consultant ======
== Nick.Roberts@dial.pipex.com ====
== Voicemail & Fax +44 181-405 1124 ===
== ==
== I live not in myself, but I become ==
=== Portion of that around me; and to me ==
==== High mountains are a feeling, but the hum ==
======= Of human cities torture.
=========== -- Byron [Childe Harold]
Corey Ashford <yeroca7@rocketmail.com> wrote in article
<6cnj5d$bjq$1@usenet.rational.com>...
>
> David Fisher wrote in message <34EEFF9C.1D01FA5D@stellar1.com>...
> >Sorry if this is a bit basic, but learning Ada on one's own can be, er,
> >challenging.
> >
> >What are the Ada equivalents of the C functions, inp and outp, used to
> >read a byte from or send one to a memory address?
> >
> >Thanks!
> >
> >David Fisher
> >Fisher Research Corporation
> >
>
> There are a number of ways to do this in Ada. Here's one fairly simple
one:
>
> with unchecked_conversion;
> with system;
>
> type byte is mod 2*8;
> type byte_access is access byte;
> function to_byte_access is new unchecked_conversion(system.address,
> byte_access);
>
> function inp(addr: system.address) return byte is
> begin
> return to_byte_access(addr).all;
> end inp;
>
> procedure outp(addr: system.address; value: byte) is
> begin
> to_byte_access(addr).all := value;
> end outp;
next prev parent reply other threads:[~1998-02-22 0:00 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-02-21 0:00 question re Ada equivalent of C function David Fisher
1998-02-21 0:00 ` Brian Rogoff
1998-02-21 0:00 ` Jerry van Dijk
1998-02-21 0:00 ` David Fisher
1998-02-22 0:00 ` Simon Wright
1998-02-22 0:00 ` Simon Wright
1998-02-22 0:00 ` Jerry van Dijk
1998-02-22 0:00 ` Robert Dewar
1998-02-22 0:00 ` Andi Kleen
1998-02-21 0:00 ` Robert Dewar
1998-02-22 0:00 ` Brian Rogoff
1998-02-22 0:00 ` Nick Roberts
1998-02-22 0:00 ` frc
1998-02-21 0:00 ` Robert Dewar
1998-02-21 0:00 ` Corey Ashford
1998-02-22 0:00 ` Nick Roberts [this message]
1998-02-22 0:00 ` Larry Kilgallen
1998-02-22 0:00 ` frc
1998-02-22 0:00 ` Linux/POSIX packages for GNAT Markus Kuhn
1998-02-22 0:00 ` Andi Kleen
1998-02-22 0:00 ` Markus Kuhn
1998-02-22 0:00 ` Robert Dewar
1998-02-22 0:00 ` Samuel Tardieu
1998-02-23 0:00 ` Nick Roberts
1998-02-23 0:00 ` Samuel Tardieu
1998-03-05 0:00 ` Testing exception handlers James M. Darlack
1998-02-22 0:00 ` Linux/POSIX packages for GNAT Robert Dewar
1998-02-23 0:00 ` Andi Kleen
1998-02-22 0:00 ` Robert Dewar
1998-02-23 0:00 ` Markus Kuhn
1998-02-23 0:00 ` Robert Dewar
1998-02-23 0:00 ` Markus Kuhn
1998-02-23 0:00 ` Robert Dewar
1998-02-23 0:00 ` Markus Kuhn
1998-02-24 0:00 ` question re Ada equivalent of C function Dale Stanbrough
1998-02-22 0:00 ` Robert Dewar
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