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=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.101.73.198 with SMTP id t6mr19520571pgs.181.1505647856269; Sun, 17 Sep 2017 04:30:56 -0700 (PDT) X-Received: by 10.36.211.15 with SMTP id n15mr381527itg.5.1505647856217; Sun, 17 Sep 2017 04:30:56 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!weretis.net!feeder4.news.weretis.net!border2.nntp.ams1.giganews.com!nntp.giganews.com!peer03.ams1!peer.ams1.xlned.com!news.xlned.com!peer01.am4!peer.am4.highwinds-media.com!peer01.iad!feed-me.highwinds-media.com!news.highwinds-media.com!126no419449itl.0!news-out.google.com!p6ni4235itp.0!nntp.google.com!126no419445itl.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Sun, 17 Sep 2017 04:30:55 -0700 (PDT) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=2a01:c22:720c:eb00:a88d:7d20:2d2:58f3; posting-account=rmHyLAoAAADSQmMWJF0a_815Fdd96RDf NNTP-Posting-Host: 2a01:c22:720c:eb00:a88d:7d20:2d2:58f3 References: <87wp4y8vkn.fsf@jacob-sparre.dk> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: FIFO From: AdaMagica Injection-Date: Sun, 17 Sep 2017 11:30:56 +0000 Content-Type: text/plain; charset="UTF-8" X-Received-Body-CRC: 1607138788 X-Received-Bytes: 3814 Xref: news.eternal-september.org comp.lang.ada:48168 Date: 2017-09-17T04:30:55-07:00 List-Id: Am Samstag, 16. September 2017 20:32:36 UTC+2 schrieb Frank Buss: > generic > Size : Positive; > type Item is private; > package Ringbuffers is > > type Ringbuffer is tagged private; > > procedure Write (Self : in out Ringbuffer; e : Item); > function Read (Self : in out Ringbuffer) return Item; > function Is_Empty (Self : Ringbuffer) return Boolean; > > private > > type Item_Array is array (1 .. Size) of Item; > pragma Volatile (Item_Array); > type Ringbuffer is tagged record > Read_Index : Positive := 1; > Write_Index : Positive := 1; > Items : Item_Array; > end record; > pragma Volatile (Ringbuffer); Please check Volatile in the RM. > > end Ringbuffers; > > > ringbuffers.adb: > > package body Ringbuffers is > > procedure Write (Self : in out Ringbuffer; e : Item) is Check for overflow is missing. > begin > Self.Items (Self.Write_Index) := e; > Self.Write_Index := Self.Write_Index + 1; > if (Self.Write_Index = Size) then Seems the true size is Size -1 , component with index Size will never be written (nor read, see below). > Self.Write_Index := 1; > end if; > end Write; > > function Read (Self : in out Ringbuffer) return Item is Check for emptiness is missing. > Result : Item; > begin > Result := Self.Items (Self.Read_Index); > Self.Read_Index := Self.Read_Index + 1; > if (Self.Read_Index = Size) then > Self.Read_Index := 1; > end if; > return Result; > end Read; > > function Is_Empty (Self : Ringbuffer) return Boolean is > begin > return Self.Write_Index = Self.Read_Index; > end Is_Empty; > > end Ringbuffers; > > > test_ringbuffer.adb: > > with Interfaces; use Interfaces; > with Ada.Text_IO; use Ada.Text_IO; > with Ringbuffers; > > procedure Test_Ringbuffer is > package FIFO_Package is new Ringbuffers (256, Unsigned_8); > subtype FIFO is FIFO_Package.Ringbuffer; > Test : FIFO; > > begin > Test.Write (1); > Test.Write (7); > while not Test.Is_Empty loop > Put_Line (Unsigned_8'Image (Test.Read)); > end loop; > end Test_Ringbuffer; > > > -- > Frank Buss, http://www.frank-buss.de > electronics and more: http://www.youtube.com/user/frankbuss