(*****************************************************************************)
(* *)
(* Truth *)
(* *)
(* 10/25/95 *)
(* Randall L. Hyde *)
(* Copyright 1995, All Rights Reserved Unless Otherwise Noted *)
(* *)
(* This program converts truth tables into logic equations. *)
(* *)
(* Runs under Windows 3.1, Windows 95, and Windows NT. *)
(* Source Code: Borland Delphi (object Pascal). *)
(* *)
(*****************************************************************************)
unit Truthu;
interface
uses
SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
Forms, Dialogs, StdCtrls, ExtCtrls, Converts, Aboutp;
type
{ Class definition for the conversion form }
TTruthTbl = class(TForm)
tt00: TPanel; {These panels correspond to the entries in the }
tt01: TPanel; {truth table, e.g., tt[0..3][0..3] }
tt02: TPanel;
tt03: TPanel;
tt10: TPanel;
tt11: TPanel;
tt12: TPanel;
tt13: TPanel;
tt20: TPanel;
tt21: TPanel;
tt22: TPanel;
tt23: TPanel;
tt30: TPanel;
tt31: TPanel;
tt32: TPanel;
tt33: TPanel;
Line1: TPanel;
Line2: TPanel;
dc00: TLabel;
dc01: TLabel;
dc10: TLabel;
dc11: TLabel;
ba00: TLabel;
ba01: TLabel;
ba10: TLabel;
ba11: TLabel;
Eqn1: TLabel; {This is where we store the logic eqn string }
Eqn2: TLabel;
TwoVarsBtn: TButton;
ThreeVarsBtn: TButton;
FourVarsBtn: TButton;
ExitBtn: TButton;
AboutBtn: TButton;
PrintBtn: TButton;
PrintDialog: TPrintDialog;
procedure TwoVarsBtnClick(Sender: TObject);
procedure ThreeVarsBtnClick(Sender: TObject);
procedure FourVarsBtnClick(Sender: TObject);
procedure tClick(Sender: TObject);
procedure ExitBtnClick(Sender: TObject);
procedure AboutBtnClick(Sender: TObject);
procedure PrintBtnClick(Sender: TObject);
end;
{Instance variable for this form }
var
TruthTbl: TTruthTbl;
implementation
{$R *.DFM}
(* ComputeEqn- Computes the logic equation string from the current *)
(* truth table entries. *)
procedure ComputeEqn;
{ ApndStr- item contains '0' or '1' -- the character in the}
{ current truth table cell. theStr is a string }
{ of characters to append to the equation if item }
{ is equal to '1'. }
procedure ApndStr(item:char; const theStr:string);
begin
with TruthTbl do begin
{ To make everything fit on our form, we have to break }
{ the equation up into two lines. If the first line }
{ hits 66 characters, append the characters to the end }
{ of the second string. }
if (length(eqn1.Caption) < 66) then begin
{ If we are appending to the end of EQN1, we have to }
{ check to see if the string's length is zero. If }
{ not, then we need to stick ' + ' between the }
{ existing string and the string we are appending. }
{ If the string length is zero, this is the first }
{ minterm so we don't prepend the ' + '. }
if (item = '1') then
if (length(eqn1.Caption) = 0) then
eqn1.Caption := theStr
else eqn1.Caption := eqn1.Caption + ' + ' + theStr;
end
else if (item = '1') then
eqn2.Caption := eqn2.Caption + ' + ' + theStr;
end;
end;
begin
with TruthTbl do begin
eqn1.Caption := '';
eqn2.Caption := '';
{ Determine if two variable truth table. tt12 }
{ will only be visible if we've got a three or }
{ four variable truth table. }
if (not tt12.Visible) then begin
{ Test the 2x2 square in the upper left }
{ hand corner of the truth table and build }
{ the logic equation from the values in }
{ these squares. }
ApndStr(tt00.Caption[1],'B''A''');
ApndStr(tt01.Caption[1],'B''A');
ApndStr(tt10.Caption[1], 'BA''');
ApndStr(tt11.Caption[1], 'BA');
end
else begin {We've got three or four variables here }
{ See if three or four variable truth table }
{ tt20 will only be visible if we have a }
{ four variable truth table. }
if (not tt20.Visible) then begin
{ Build the logic equation from the top }
{ eight squares in the truth table. }
ApndStr(tt00.Caption[1],'C''B''A''');
ApndStr(tt01.Caption[1],'C''B''A');
ApndStr(tt02.Caption[1], 'C''BA''');
ApndStr(tt03.Caption[1], 'C''BA');
ApndStr(tt10.Caption[1],'CB''A''');
ApndStr(tt11.Caption[1],'CB''A');
ApndStr(tt12.Caption[1], 'CBA''');
ApndStr(tt13.Caption[1], 'CBA');
end
else begin {We've got a four-variable truth table }
{ Build the logic equation from all the squares }
{ in the truth table. }
ApndStr(tt00.Caption[1],'D''C''B''A''');
ApndStr(tt01.Caption[1],'D''C''B''A');
ApndStr(tt02.Caption[1], 'D''C''BA''');
ApndStr(tt03.Caption[1], 'D''C''BA');
ApndStr(tt10.Caption[1],'D''CB''A''');
ApndStr(tt11.Caption[1],'D''CB''A');
ApndStr(tt12.Caption[1], 'D''CBA''');
ApndStr(tt13.Caption[1], 'D''CBA');
ApndStr(tt20.Caption[1],'DC''B''A''');
ApndStr(tt21.Caption[1],'DC''B''A');
ApndStr(tt22.Caption[1], 'DC''BA''');
ApndStr(tt23.Caption[1], 'DC''BA');
ApndStr(tt30.Caption[1],'DCB''A''');
ApndStr(tt31.Caption[1],'DCB''A');
ApndStr(tt32.Caption[1], 'DCBA''');
ApndStr(tt33.Caption[1], 'DCBA');
end;
end;
{ If after all the above the string is empty, then we've got a }
{ truth table that contains all zeros. Handle that special }
{ case down here. }
if (length(eqn1.Caption) = 0) then
eqn1.Caption := '0';
Eqn1.Caption := 'F= ' + Eqn1.Caption;
end;
end;
{ If the user hits the "Two Variables" button, turn off all the squares }
{ in the truth table except the upper left 2x2 block. Change the labels}
{ on the truth table as appropriate. }
procedure TTruthTbl.TwoVarsBtnClick(Sender: TObject);
begin
ba00.Caption := 'A''';
ba01.Caption := 'A';
ba10.Caption := '';
ba11.Caption := '';
dc00.Caption := 'B''';
dc01.Caption := 'B';
dc10.Caption := '';
dc11.Caption := '';;
tt02.Visible := false;
tt03.Visible := false;
tt12.Visible := false;
tt13.Visible := false;
tt20.Visible := false;
tt21.Visible := false;
tt22.Visible := false;
tt23.Visible := false;
tt30.Visible := false;
tt31.Visible := false;
tt32.Visible := false;
tt33.Visible := false;
Eqn2.Visible := false;
tt02.Caption := '0';
tt03.Caption := '0';
tt12.Caption := '0';
tt13.Caption := '0';
tt20.Caption := '0';
tt21.Caption := '0';
tt22.Caption := '0';
tt23.Caption := '0';
tt30.Caption := '0';
tt31.Caption := '0';
tt32.Caption := '0';
tt33.Caption := '0';
ComputeEqn;
end;
{ If the user presses the "Three Variables" button, turn off the bottom }
{ eight squares and adjust the labels as appropriate. This code also }
{ turns on any squares turned off by TwoVarsBtnClick above. }
procedure TTruthTbl.ThreeVarsBtnClick(Sender: TObject);
begin
ba00.Caption := 'B''A''';
ba01.Caption := 'B''A';
ba10.Caption := 'BA''';
ba11.Caption := 'BA';
dc00.Caption := 'C''';
dc01.Caption := 'C';
dc10.Caption := '';
dc11.Caption := '';;
tt02.Visible := true;
tt03.Visible := true;
tt12.Visible := true;
tt13.Visible := true;
tt20.Visible := false;
tt21.Visible := false;
tt22.Visible := false;
tt23.Visible := false;
tt30.Visible := false;
tt31.Visible := false;
tt32.Visible := false;
tt33.Visible := false;
Eqn2.Visible := true;
tt20.Caption := '0';
tt21.Caption := '0';
tt22.Caption := '0';
tt23.Caption := '0';
tt30.Caption := '0';
tt31.Caption := '0';
tt32.Caption := '0';
tt33.Caption := '0';
ComputeEqn;
end;
{ This procedure turns on all the squares when the user presses }
{ the "Four Variables" button. }
procedure TTruthTbl.FourVarsBtnClick(Sender: TObject);
begin
ba00.Caption := 'B''A''';
ba01.Caption := 'B''A';
ba10.Caption := 'BA''';
ba11.Caption := 'BA';
dc00.Caption := 'D''C''';
dc01.Caption := 'D''C';
dc10.Caption := 'DC''';
dc11.Caption := 'DC';;
tt02.Visible := true;
tt03.Visible := true;
tt12.Visible := true;
tt13.Visible := true;
tt20.Visible := true;
tt21.Visible := true;
tt22.Visible := true;
tt23.Visible := true;
tt30.Visible := true;
tt31.Visible := true;
tt32.Visible := true;
tt33.Visible := true;
Eqn2.Visible := true;
ComputeEqn;
end;
{ Whenever the user clicks on one of the squares in the truth table, }
{ this procedure toggles its label between '0' <-> '1'. }
procedure TTruthTbl.tClick(Sender: TObject);
var t:TPanel;
begin
t:=TPanel(Sender);
t.Caption := chr(ord(t.Caption[1]) xor 1);
ComputeEqn;
end;
procedure TTruthTbl.ExitBtnClick(Sender: TObject);
begin
Halt;
end;
procedure TTruthTbl.AboutBtnClick(Sender: TObject);
begin
AboutBox.Show;
end;
procedure TTruthTbl.PrintBtnClick(Sender: TObject);
begin
if (PrintDialog.Execute) then
TruthTbl.Print;
end;
end.
