1--
2-- Copyright(C) 1998
3-- All Rights Reserved. Salih Yurttas, ZCubes, BitsOfCode Software Systems, Inc..
4--
5-- Permission to use, copy, modify, and distribute this
6-- software and its documentation for EDUCATIONAL purposes
7-- and without fee is hereby granted provided that this
8-- copyright notice appears in all copies.
9--
10
11-- date : January 1, 1998.
12-- author : Salih Yurttas.
13
14-- queue_01_p.adb
15
16
17package body Queue_01_P is
18
19 Queue_Size : constant Integer := 10;
20 subtype Queue_Index is Integer range 0..Queue_Size-1;
21
22 Queue_Head : Queue_Index;
23 Queue_Length : Integer range 0..Queue_Size;
24 Queue_Body : array(Queue_Index) of Float;
25
26 function Full return Boolean is
27 begin
28 return Queue_Length = Queue_Size;
29 end Full;
30
31 function Empty return Boolean is
32 begin
33 return Queue_Length = 0;
34 end Empty;
35
36 procedure Enqueue(E : in Float) is
37 begin
38 if Full then
39 raise Overflow;
40 end if;
41
42 Queue_Body((Queue_Head+Queue_Length) mod Queue_Size) := E;
43 Queue_Length := Queue_Length + 1;
44 end Enqueue;
45
46 function Dequeue return Float is
47 E : Float := Queue_Body(Queue_Head);
48 begin
49 if Empty then
50 raise Underflow;
51 end if;
52
53 Queue_Head := (Queue_Head+1) mod Queue_Size;
54 Queue_Length := Queue_Length - 1;
55
56 return E;
57 end Dequeue;
58
59begin
60
61 Queue_Head := 0;
62 Queue_Length := 0;
63
64end Queue_01_P;