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=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,146880aa5d8c64c7
X-Google-Attributes: gid103376,public
From: Stephen Leake <Stephen.Leake@gsfc.nasa.gov>
Subject: Re: Array of tasks
Date: 1997/12/09
Message-ID: <348DC3C0.7555@gsfc.nasa.gov>#1/1
X-Deja-AN: 296727220
References: <348D7832.27A4@assist.org>
Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA
Reply-To: Stephen.Leake@gsfc.nasa.gov
Newsgroups: comp.lang.ada
Date: 1997-12-09T00:00:00+00:00
List-Id: <comp.lang.ada>


Larry Coon wrote:
> 
> I have an array of tasks and an array of semaphores.
> The size of both arrays are set at runtime (based on
> user input).  I can't figure out a way to make the
> array of semaphores visible to the array of tasks.
> 
> Here's some contrived code to illustrate what I'm
> trying to do:
>
>   <fixed code below>
>
> Within the body of task T I want to access a semaphore in
> semaphore_array.  It won't compile, saying the semapore
> array is not visible.
> 
> How do I declare things so the tasks can see the semaphores?
> I've tried nested blocks, and I've tried passing pointers
> to the semaphores, but couldn't get anything to work right.
> Thanks in advance for any help.
> 

I was hoping an access discriminant would do the trick, but I ended up
with dynamically allocating the semaphores. Maybe you can fiddle some
more. I added the bodies so others can compile if they want.

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO;
procedure Test is
  protected type semaphore is
    entry seize;
    procedure release;
  private
    available:  boolean := true;
  end semaphore;

  -- The usual implementation of a semaphore.
  protected body semaphore is separate;

  type Semaphore_Array_Type is array (Integer range <> ) of semaphore;
  type Semaphore_Array_Access_Type is access all Semaphore_Array_Type;
  task type T (Semaphore_Array : Semaphore_Array_Access_Type);
  task body t is separate;

  task_count: positive;
begin -- main
  put ("Enter number of tasks: ");
  Ada.Integer_Text_IO.get (task_count);
  declare
    subtype task_range is integer range 1..task_count;
    Semaphore_Array : Semaphore_Array_Access_Type (task_range) :=
new        Semaphore_Array_Type (Task_Range);
    subtype Specific_Task is T (Semaphore_Array);
    task_array: array (task_range) of Specific_Task;
  begin
    null;
  end;
end Test;

separate (Test)
protected body semaphore is
   entry Seize when Available is
   begin
      Available := False;
   end Seize;

   procedure Release
   is begin
      Available := True;
   end Release;
end semaphore;

separate (Test)
task body T is
begin
   Semaphore_Array (1).Seize;
end T;

> Larry Coon
> University of California
> larry@assist.org
> and lmcoon@home.com

-- 
- Stephe