CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
TRACING
THE MINIMAL-SPANNING TREE
ALGORITHMS
A graduate project submitted in partial satisfaction
of the requirements for the degree of Master of Science in
Computer Science
By
Shi-Chung Liu
August, 1984
The Graduate Project of Shi-Chung Liu is approved:
Robert
Ja
Wong
D. Alanen
Bob Henderson, Chair
California State University, Northridge
ii
ACKNOWLEDGEMENT
I like to thank Dr. Bob Henderson for his continued
assistance and advice, as well as Dr. Jack Alanen and
Dr. Robert Wong for their encouragement.
I
also want to express my appreciation to my wife for her
patience and encouragement during the course of this
work.
iii
TABLE OF CONTENTS
ACKNOWLEDGEMENT ••••••••••••••••••••••••••••••
iii
LIST OF TABLES • • • • • • • • • • • • • • • • • • • • • • • • • • • • . • •
vi
LIST OF FIGURES ••••••••••••••••••••••••••••••
vii
ABSTRACT • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
i
Chapter 1
X
INTRODUCTION
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . .
1
1.2 Project Description ••••••••••••••
4
Chapter 2
SIMULATION TYPE CAl --- SCAI
2.1 The Behavior of SCAI •••••••••.•.•
7
2.2 Requirements
9
2.3 Overall Design •••••••••••••••••••
11
2.4 Graph Representation •••••••••••••
21
2.5 Program Structure ••••••••••••••••
25
Chapter 3
EXTERNAL PROCEDURES --- TRACE.STUFF
3.1 Requirements •••••••••••••••••••••
27
3.2 Functional Specification •••••••••
29
3.3 Data Structures ••••••••••••••••••
34
iv
3.4 Modular Design •••••••••••••••••••
38
3.5 Error Prevention •••••••••••••••••
43
Chapter 4
CAl GENERATOR --- CAI.WRITER
4.1 Hardware/Software Specification
48
4.2 Input/Output Specification •••••••
49
4.3 Internal Design ••••••••••••••••••
53
Chapter 5
GRAPH EDITOR --- GRAPH.GEN
5.1 Requirements •••••••••••••••••••••
55
5.2 Overall Design •••••••••••••••••••
56
Chapter 6
CONCLUSIONS
6.1 Discussion
65
6.2 Further Improvements •••••••••••••
68
REFERENCES • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
69
Appendix A
EXAMPLES •••••••••••••••••••••••••
70
Appendix B
PROGRAM LISTING ••••••••••••••••••
88
v
LIST OF TABLES
Table 2.3.6
Summary of User-Interaction
in a SCAI
Table 3.5.1
20
Status Checking of TRACE.STUFF
External Procedure Calls
Table 6.1.1
46
The Restrictions of Apple
Pascal
......................
vi
67
LIST OF FIGURES
Fig. 1.1.1
Ideal Dialogue with Smart
System......................
Fig. 1.2.1
Data Flow Diagram of
CAI.WRITER ..••...........•••
Fig. 2.3.1
Overall Design of SCAI
Fig. 2.3.2
A Snapshot of Action 1 in
Prim's MST Algorithm ••••••••
Fig. 2.3.3
. . . . . . . . . . . . . . . ... .
12
13
15
A Snapshot of Action 3 in
Algorithm ODDSQUARE
Fig. 2.3.5
5
The Breakpoints in Algorithm
ODDSQUARE
Fig. 2.3.4
2
17
A Snapshot of Action 4 in
Algorithm ODDSQUARE
19
Fig. 2.4.1
Representation of a Graph ••••
22
Fig. 2.4.2
Vertex and Edge Representation
23
Fig. 2.4.3
Representation of a Graph and
Its Minimal Spanning Tree •••
Fig. 2.5.1
24
The Main Program of the SCAI
for Algorithm ODDSQUARE •••••
Fig. 3.4.1
Modular Design of TRACE.STUFF
Fig. 3.4.2
Data Flow Between Module
26
40
INTERFACE and the Internal
Modules . . • . . • . . . • . . • • • . . . . . .
vii
41
Fig. 4.2.1
Input/Output of CAI.WRITER
50
Fig. 5.2.1
The Main Menu of GRAPH.GEN
57
Fig. 5.2.2
Locating the Vertices
57
Fig. 5.2.3
Before Entering the
61
Fig. 5.2.4
Entering the Edges and Their
Fig. 5.2.5
. . . .. .. .. . . . . .. . . . . . . . . .
Saving the Graph Data . . . . -. . .
Cost
viii
. . .... . .
Edges ....
62
64
ABSTRACT
TRACING
THE MINIMAL-SPANNING TREE
ALGORITHMS
by
Shi-Chung Liu
Master of Science in Computer Science
A Computer Aided Instruction <CAl) model is designed for
presenting most algorithms; it contains the following
main features:
user selected breakpoints
double screens presentation
visible and reversible execution
hardcopy of trace
For saving the CAl package development time, a
preprocessor called CAI.WRITER is implemented for helping
the CAl programmer to generate the CAl package.
By using
this preprocessor, the CAl programmer only needs to
ix
implement the algorithm and to create the tutorial text
files.
The job of detailed coding in CAl is left to
CAI.WRITER.
Appendix A shows two examples of using
CAI.WRITER.
Program is written in UCSD Pascal on a 64K Apple //e two
disk drives system, as lists on Appendix B.
Chapter 6
discusses the advantages and limitation of using Apple
system to develope a large program.
X
Chapter 1
INTRODUCTION
1.1 Motivation
With the proliferation of computers, many CAl
<computer
aided instruction> packages were implemented for numerous
fields of education.
Informally speaking, a CAl package
can be treated as a video tape that is connected to a
remote control device.
It is user-friendly, in that the
user can re-play some part of the tape by means of
'rewind' and 'forward'.
Some CAis are user-interactive,
requiring the user to talk to the tape.
This is such a
nice device for learning something, that most people
agree CAis are effective teaching tools.
However, to implement a CAI package is rather time
consuming.
The future may provide an ideal Smart System
for CAI programmers to produce any CAl package.
in Fig.
As shown
1.1.1, the CAl programmer gives the highest
level of package specification to the Smart System, and a
CAl package would be generated automatically.
Software packages are developed based on people's needs.
For instance, word processing packages are implemented
for report writing, statistical analysis packages are
1
2
Programaer:
Saart Systea:
I need a CAl package.
OK, for which field ?
Accounting
Biology
Cheaistry
Computer Science
Prograa;er:
Saart Systea:
Coaputer Science.
for which sub-field ?
Algorithm
Coapiler
Data Base Systea
Language
Programmer:
Smart System:
Algorithm.
Which algoritha 1 and where can I find it ?
Programaer:
Saart System:
Pria's MST algoritha 1 on Disk I 10, File 'PRIM. TEXT'.
Please specify the following:
t1l Host Machine
t2l Options beside the standard CAl
option 1:
option 2: ..........
Prograamer:
Smart Systea:
Apple //e, standard CAl
ACAl package for Prim's MST algoritha is generated,
and on Disk I 10 1 Files 'PRIM.CAI.TEXT' and 'PRIM.CAI.CODE'.
Fig. 1.1.1
Ideal Dialogue with Smart System
3
generated for data analysis, and data base management
systems are invented for helping people to store and
retrieve data.
As we can see, time saving and accuracy
guarantee are two primary motivations for developing
these packages.
If the Smart System does save CAl
package development time and is reliable, then there is
every reason why we want it.
The Brown University Algorithm Simulator and Animator•
<BALSA> employed some automatic processes for generating
algorithm courseware.
It is reported that each lecture
required only five to seventeen hours of courseware
development time.
This points out that part of the Smart
System can be done today.
This project is a small subset of the ideal Smart System.
It can help the CAl programmer to generate a CAl package
for most algorithms.
4
1.2 Project Description
The object of this project was to write a CAI package for
Minimal-Spanning Tree <MST> algorithms.
It would show
the behavior of two different MST algorithms to students.
However, in order to save on package development time and
avoid redundent code, some external procedures called
TRACE.STUFF were written first.
These procedures are
common to most of the algorithm CAI packages.
With
TRACE.STUFF it is easy to write a CAl package for an
algorithm:
STEP 1:
implement the algorithm as a UCSD
Pascal program
STEP 2:
include the declaration of TRACE.STUFF
as part of the declaration of this
program
STEP 3:
insert some appropriate external
procedure calls of TRACE.STUFF into
this program
The second step is easy by employing the UCSD Pascal
'include directives·, but the third step is tedious to
do.
One interesting point is that most of the insertions
are predictable.
From this point came the idea of
using a code generator to include the external
procedures declaration, and to insert some
5
external procedure calls into the source code.
The final version of the program contains two parts
CAI.WRITER and GRAPH.GEN.
They are written in UCSD
Pascal on an 64K Apple lie two disk drives microcomputer
system.
CAI.WRITER is a preprocessor in front of SYSTEM.COMPILER.
The input to CAI.WRITER is a UCSD Pascal source program
<hereafter referred to as the 'algorithm'} and some
tutorial TEXT files.
The output is a source program in
UCSD Pascal plus TRACE.STUFF, acting as a simulaion type
CAl (hereafter referred to as SCAI> for this input
algorithm.
Fig.
1.2.1 shows a simplified data flow
diagram for CAI.WRITER.
After compiling SCAI, the user
can see an algorithm in action as each ·statement is
executed and view the animation of the tree development
process.
Snapshots of the tree development process are
also output to a printer.
-Tutorial TEXT files _ __.
CAI.WRITER
-Algorithm TEXT file
1---
CAl Package ---
----4~...__ _ _ _ _ _.J
Fig. 1.2.1
Data Flow Diagram of CAI.WRITER
6
GRAPH.BEN, a user-interactive subprogram written in Apple
BRAFMODE, allows the user to create graphic data easily,
and to save data on diskette for later use.
In the following chapters we will discuss the
requirements, design, and implementation for the
following four systems:
<1> SCAI
The output of CAI.WRITER, a package written
in Pascal plus TRACE.STUFF, acts as a
simulation type CAl for an algorithm.
<2> TRACE.STUFF
A set of external procedures specialized
for program and graph tracing.
(3) CAI.WRITER
A system for generating SCAI.
(4) GRAPH.BEN
A system for generating graphic data.
Chapter 2
SIMULATION TYPE CAl --- SCAI
2.1 The Behavior of SCAI
SCAI <a Simulation type CAl> has three modes:
introduction-mode, selection-mode, and tracing-mode.
Tracing-mode is valid only when the selection-mode has
been done.
None of these three modes can be nested in
another.
Introduction-mode is used to describe the algorithm which
SCAI will trace or to explain how to use this package.
Selection-mode allows the user to select a set of
user-breakpoints in the algorithm, and select a graphic
data from a graph library.
In the tracing-mode, SCAI simulates the execution of the
algorithm.
If a statement is an assignment statement and
the left operand is of type integer, character, or real,
then the value of that operand will be displayed.
SCAI
stops the trace and interacts with the user at each
user-breakpoint.
User can control the execution of the
algorithm step by step in two directions:
backward.
forward and
Some commamds are available for the user to
7
8
get rid of the user-interaction.
9
2.2 Requirements
This section serves to document the requirements analysis
and specification for the CAl model SCAI.
The purpose of SCAI for an algorithm is to get the user
involved in the execution of this algorithm.
SCAI must
have some way to show the algorithm execution to the
user, and allow the user to control the execution.
SCAI
must be able to show as many variable values of each
statement as possible, and also allow the user to
transfer the algorithm trace to hard-copy at anytime.
For SCAI of a graphic algorithm, SCAI must be able to
show the user what the graph <or tree> looks like, in
addition to the algorithm trace.
Because SCAI is
designed for students with minimal programming
background, the display of a graph should be understood
by at least 90 % of Computer Science majors.
The graph
trace and the algorithm trace must be shown
simultaneously on the screen, or be switched within 1
second if they are on different pages.
SCAI must have the flexibility to allow the user to input
their own graphic data and specify any set of
breakpoints.
10
The Pascal Operating System4 on the Apple II computers
uses single letter commands.
for Filer.
For instance,
'F' stands
Because SCAI is running under this
environment and to make all the command formats
consistent, SCAI should provide a set of single letter
commands for the user-interaction.
11
2.3
Fig.
Overall Design
2.3.1 shows the overall design of SCAI.
The first
column presents the action flow of SCAI, the second
column specifies the action mode, and the third column
indicates which screen mode is used for each action.
TEXT means a 24-lines x SO-columns text display mode.
GRAPH means a 192 x 280 pixels resolution graphic mode.
Both action 1 <present the user algorithm> and action 5
(discussion> use INTRODUCTION mode.
This mode provides
the user with two introduction-control commands:
command
function
prompt
N
N>ext
continue the text file display
Q
Q>uit
stop this action
The contents of a text file are displayed double spaced
on the bottom 20 lines of TEXT screen.
Enabling the user
to use these commands easily, the TEXT screen shows a
prompt of the commands on the top.
Fig.
2.3.2 is a
snapshot of action 1 in the SCAI of Prim's MST
algorithm~.
Action 1 displays a text file containing
information about the user algorithm or the user's
manual.
Action 5 displays a text file which discusses
this algorithm's performance.
It is the programmer's
responsbility to create these text files.
12
Action
Action
Mode
Screen
Mode
INTRODUCTION
TEXT
SELECTION
GRAPH
SELECTION
TEXT
TRACING
TEXT &
GRAPH
INTRODUCTION
TEXT
(Start
1 :
Present the
algorithm
::z:
Select
a graph
3:
Select a set of
breakpoints
4:
Simulate the
algorithm
~=
Discussion
(End
Fig. 2.3.1
Overall Design of SCAI
13
Introduction:
N>ext
G>uit
Suppose 6 = IV,El is a connected graph in which each edge (u 1 vl in E has
a cost c(u 1 vl attached to it • A spanning tree for 6 is a tree that
connects all the vertices in V. The cost of a spanning tree is the sum
of the edges in the tree. In this package we shall show how to find a
minimal spanning tree for 6.
A typical application for minimum-cost spanning trees occurs in the design
of communications
networ~s.
The vertices of a graph represent cities and
the edges possible coeeunications links between the cities. The cost
associated with an edge represents the cost of selecting that link for the
Fig. 2.3.2
A Snapshot of Action 1 in
Prim's MST Algorithm
14
In action 2
(select a graph>, the user can select an
existing graph.
This graph is plotted to a printer and
marked 'Original' if a printer is on line.
For the user
interested in their own graph, it must first be created
by using the GRAPH.GEN system.
A breakpoint of the algorithm is defined as a separator
(semicolon) in its Pascal main program.
Fig.2.3.3 shows
all the breakpoints and their sequence numbers in a
simple algorithm ODDSQUARE 9
,
the sequence number of a
breakpoint is an integer greater than 1.
A set of
commands called selection-control commands is available
for action 3
command
u
(select a set of breakpoints>.
prompt
U>p
They are:
function
move the pointer up to the
last breakpoint of the
algorithm
D
D>own
move the pointer down to the
next breakpoint of the
algorithm
s
S>elect
select the current pointer
position as a user-breakpoint
F
F>ree
reset the current pointer
position free as a breakpoint
p
P>rint
transfer the contents of TEXT
15
BEGIN (f HAIN fl
WRITELN!'INPUT N, PLEASE.
READLN!N ; 3
·~~
S:=~
B := Q 5
-------
FORK := 1 TON DO
BE6IN
--------=::::::
breakpoints
s := s +
: b
_//
B:=B+~/
EN , B
END.
Fig. 2.3.3
The Breakpoints in Algorithm
ODDS QUARE
16
screen to a printer if it is
available
Q
Fig.
Q)uit
stop action 3
2.3.4 shows a snapshot of action 3 in the SCAI of
ODDSQUARE algorithm.
A prompt which contains the
selection-control commands is shown on the bottom line.
Because the Apple II+ has a 40 column TEXT screen, the
frequently used commands are arranged to appear on the
left hand side of the prompt line.
The text of the
algorithm is shown on the top 22 lines of TEXT screen.
The pointer position is indicated by the screen console.
The breakpoint is identified with a mark '(-------' when
it is selected by the user.
Some algorithms are too long to fit onto the screen, so
when the pointer reaches the top or the bottom, the
algorithm will be scrolled down or up.
After action 2, a
subset of the breakpoints selected by the user, will be
known as the user-breakpoints.
Action 4 (simulate the user algorithm> is the main action
of SCAI.
It simulates each statement throughout the user
algorithm and interacts with the user if a
user-breakpoint is reached.
At all of the
user-breakpoints, a set of trace-control commands is
available to the user:
17
BESIN
(t
MAIN +.l
WRITELN<~INPUT
N, PLEASE. '};
READLN (tll;
s :=
0;
B := 1;
<-------
FDR K := I TO NDO
3E5IN
S : = 5 + B:
B := B + 2; <-------1
END;
END.
Select Breakpoints: U>p D>own S>elert F>ree P>rint Q)uit
Fig. 2.3.4
A Snapshot of Action
Algorithm ODDSQUARE
~
in
18
command
B
prompt
function
B>ackup
back up the algorithm one
user-breakpoint
N
N>ext
execute the algorithm one
user-breakpoint
T
T>race
show the TEXT screen
G
G>raph
show the GRAPH screen
p
P>rint
transfer the contents of the
TEXT screen to a printer if
it is available
E
E>nd
execute the algorithm to end
Q
Q)uit
execute the algorithm to end
and stop action 4
Each of these commands acts independently.
For example,
the user need not enter 'T' before printing the TEXT
screen.
The screen format is the same as that from
action 3, the bottom line is a prompt and the top 22
lines are the text of the algorithm and trace.
Fig.
2.3.5 is a snapshot of action 4 in the SCAI of the
ODDSQUARE algorithm.
Table 2.3.6 is a summary of prompts for user-interaction
commands in a SCAI.
the prompt.
The command is the first letter of
19
BESIN
I* MAIN t)
INPUT N, PLEASE •. l;
READLNlNl; 9
~RITEUH'
s := 0;
INPUT N, PLEASE.
(!
B : = 1: 1
FOR K := 1 TO
NDO
BEE IN
B := B + 2; 3 I
Erm;
END.
Tracing: N>ext B>ackup T>ext 6}raph E>nd P>rint Q}uit
Fig.
A Snapshot of Action 4 in
Algorithm ODDSQUARE
20
Introductioncontrol
Selectioncontrol
Tracingcontrol
N>e>:t
U>p
B>ackup
Q)uit
D>own
N>ext
S>elect
T>race
F>ree
G>raph
P>rint
P>rint
Q)uit
E>nd
Q)uit
Table 2.3.6
Summary of User-Interaction in A SCAI
21
2.4 Graph Representation
A graph (in mathematics> is a finite set of vertices some
of which are connected by edges.
A weighted graph is a
graph in which each edge associates with a cost 3 •
The
term 'graph' in this report always means weighted graph
unless otherwise specified.
The best way to show a graph on a computer with a high
resolution screen is by drawing the graph's diagram 10 •
Fig.
2.4.1 shows an example of a graph's diagram.
Each vertex or edge has two representations, state 1 and
state 2 as shown in Fig.
2.4.2.
One of the two states
can be used to stand for the status of ·marked',
'traveled',
'selected' in the graphic algorithms.
For
instance, MST algorithms use state 2 for the status
'selected', so the original graph and the Minimal
Spanning Tree can be shown on the same diagram.
2.4.3)
<Fig.
22
;_A __:
.-6-
: B
l
--
-~-~--------s-------- :· C ·:---------5·-------:
D ·:
:: E::-----------6----------:---F--:
Fig.
2.4.1
Representation of a Graph
23
State 1
verte>:
F
State ...,
.L.
.r~~ ••
( F 'I
...._~f
edge
i
:
Fig. 2.4.2
I
I
1.
Vertex and Edge Representation
24
(p;--.,
•• ....__
.-.
.-----·-.... .• .•
.... -b
(_ B )-----
5
-\
_,..Jf. ••
..···· T ·· ...
1.
-->- ....•
__1,_
\
>--····
___ .6·
....r---
---( c ) ....... -s-- ··· .. · t.._ D)
.. --___.oe;
/ ·-'
::3
··c-
•...4
',
/
2I
'\-../
iEl··········6··········(F)
~
rlg.
2.4.3
~~
Representation of a Graph and
Its Minimal Spanning Tree
25
2.5 Program Structure
The main program of a SCAI contains two parts, the
execution part and the simulation part.
Fig.
2.5.1
shows the main program of the SCAI for a simple algorithm
ODDSQUARE.
Execution part performs the algorithm.
The
simulation part contains the procedure calls of
TRACE.STUFF, and has nothing to do with the execution of
the algorithm but only with the simulation.
parts are merged together.
These two
Each statement in the
original algorithm program becomes two statements, one
for the execution and another for simulation.
Control is
switched between the execution and simulation parts, so
the user will feel that execution and simulation are
taking place simultaneously.
Execution part is written by the CAl programmer, and the
simulation part is generated by CAI.WRITER.
Next chapter
discusses what these simulation statements are and their
functions.
26
BEGIN
(~
MAIN
f.)
TRACE\2l;
WRITELNl'INPUT N, PLEASE.
TRACE{3i;
READLN\Nl;
s := t);
IT RACE \4, Sl;
B ! = 1;
ITRAC£{5,B);
FOR K := 1 TD N DD
BEGIN
S:=S+B;
ITRACE(6,SI;
B := B + 2;
iTRACE\7,Bl;
TRACE\Si;
END.
/
the execution part
Fig. 2.5.1
the simulation part
The Main Program of the SCAI
for Algorithm ODDSQUARE
Chapter 3
EXTERNAL PROCEDURES
TRACE. STUFF
3.1 Requirements
Chapter two defined a CAl model for algorithms.
Now the
problem is turned to how to produce a CAI package
automatically.
To achieve this goal, it is necessary to
have a set of common procedures <TRACE.STUFF> for most
CAl packages.
There are three general requirements for
TRACE. STUFF:
<1> TRACE.STUFF must be easy-to-use
<2> TRACE.STUFF must contain all the user-interaction
routines and utility procedures which are needed
to form a CAI program
(3) the structure and organization of TRACE.STUFF
must simplify the code generator CAI.WRlTER
Although other solutions are possible, the approach taken
in this project is to use:
*
*
*
meaningful procedure names
simple parameter passing
pseudo concurrent processing of execution and
simulation
*
pseudo reverse <backup> execution/simulation
<using a backup buffer)
27
28
*
user-interaction routines, pseudo concurrent
processing, and pseudo reverse execution facilities
built into appropriate procedures of TRACE.STUFF
29
3.2 Functional Specification
TRACE.STUFF contains eleven external procedures that can
be classified into the following three categories:
Category A:
procedures for data loading and
data reset
Category B:
procedures for tracing the user
program
Category C:
procedures to demonstrate the
development of a tree
Three procedures are in category A:
INITTRACE <short for
INITializing TRACE>, ENDTRACE and INTRODUCTION.
description of each procedure follows:
procedure INITTRACE < NAME :
string >
functions:
to load the text file NAME of the
algorithm and global data from diskette
to set up the selection-mode
to prompt user to select a graph data,
set up the original graph, and plot this
graph on paper
to prompt the user to specify the
breakpoints of the algorithm
to get selection-control commands (see
section 2.3) from the user and perform
A short
30
them
to initialize the tracing-mode
procedure ENDTRACE
functions:
to give the user a last chance to back up
the execution of the algorithm
to reset the algorithm text file and
breakpoints data
procedure INTRODUCTION ( NAME : string )
functions:
to set up the introduction-mode and
display a text file pointed by NAME
to get introduction-control commands <see
section 2.3> from the user and perform
them
Procedures TRACE, ITRACE <short for Integer TRACE>,
CTRACE (short for Character TRACE> and RTRACE <short for
Real TRACE> belong to category B.
They take care of the
trace of the algorithm, the following describe their
functions:
procedure TRACE < NUMBER : integer >
functions:
to move the cursor to the NUMBER-th
31
breakpoint of algorithm on the TEXT
screen
to get trace-control commands <see
section 2.3> from the user and perform
them
procedure !TRACE < NUMBER : integer;
INT : integer >
functions:
to display the value of integer INT at
the NUMBER-th breakpoint of the algorithm
on the TEXT screen
to get trace-control commands from the
user and perform them
procedure CTRACE < NUMBER : integer;
CH : char )
functions:
to display a character CH at the
NUMBER-th breakpoint of the algorithm on
the TEXT screen
to get trace-control commands from the
user and perform them
procedure RTRACE < NUMBER : integer;
REL : real >
functions:
to display the value of real number REL
at the NUMBER-th breakpoint of the
algorithm on the TEXT screen
32
to get trace-control commands from the
user and perform them
Four simple procedures are used to demonstrate the
development of a minimal-spanning tree <MST>.
By using
these procedures the changes between two consecutive
snapshots of a MST algorithm can be described.
These
procedures are VSELECT (short for Vertex SELECTed>,
VRELEASE <short for Vertex RELEASEd>, ESELECT <short for
Edge SELECT> and ERELEASE <short for Edge RELEASEd>.
short description of each procedure follows:
procedure VSELECT < Vl :
char >
functions:
to draw a solid circle around vertex Vl
on the graph screen
to plot the current graph on paper
procedure VRELEASE <Vl : char)
functions:
to draw a dotted circle around vertex Vl
on the graph screen
to plot the current graph on paper
procedure ESELECT <Vl, V2 : char>
functions:
to draw a solid line to connect vertices
A
33
Vl and V2 on the graph screen
to plot the current graph on paper
procedure ERELEASE <Vl, V2 : char)
functions:
to draw a dotted line to connect vertices
Vl and V2 on the graph screen
to plot the current graph on paper
34
3.3 Data Structures
This section describes the main data types used in
TRACE. STUFF.
Because memory is the main concern in
developing a large program on an Apple //e 2 ,
most data
types were determined by memory concerns only.
The data
structure, purpose, and components of each data type are
as follows:
Data type name
VLIST
Data structure
packed array of record
Purpose ----------- describes all the vertices in a
graph
VLIST contains at most 13 records; the first one contains
the total number of vertices, the remainder represent
vertices.
Each record of VLIST contains the three
fields:
field
NAME
meaning
identification of this
~
CHAR
vertex
X
x-coordinate on GRAPH
INTEGER
screen
y
y-coordinate on GRAPH
INTEGER
35
screen
Data type name
ELIST
Data structure
packed array of record
Purpose ----------- describes all the existed edges
in a graph.
ELIST contains at most 16 records.
As in VLIST the first
record is reserved for the total number of edges, the
remainder represent edges.
Each record of VLIST contains
the three fields:
field
meaning
~
V1
name of the start vertex
CHAR
V2
name of the end vertex
CHAR
COST
cost of this edge
INTEGER
/
Data type name
HALFPAGE
Data structure
packed array of string
Purpose ----------- aid to scrolling the screen
contents
HALFPAGE contains 11 strings indexed from 1 to 11.
In
36
the selection mode, it contains the algorithm text and
user-breakpoint mark
'<-------·.
In the tracing mode it
contains the algorithm text and trace.
At any instant,
there is at most one HALFPAGE in RAM.
Data type name
BRKTBL
Data structure
packed array of record
Purpose ----------- describes the breakpoints in an
algorithm.
The size of BRKTBL is defined as a constant.
The first
record holds the total number of breakpoints and the label
of last HALFPAGE.
The remainder present breakpoints.
Each record of BRKTBL contains the two tields:
field
PAGENO
meaning
a label used to access
~
STRING[!]
a HALFPAGE
LINENO
the index of a statement
in a HALFPAGE
Data type name
BUFFER
Data structure
packed array of record
INTEGER
37
Purpose ----------- keeps all the information needed
for backing up an algorithm.
Each record contains the three fields:
field
TI
meaning
the breakpoint number
~
INTEGER
indexed by an element
of BRKTBL
STRI
the trace for this
STRIN6[10J
breakpoint
STOP
•true·
if there will be
interaction with
the user,
'false· otherwise
BOOLEAN
38
3.4 Modular Design
Final version of TRACE.STUFF contains eight modules as
3.4.1.
shown in Fig.
One of them serves as the external
interface for the user program; it is implemented as a
set of procedures.
Five of them serve as the internal
modules, and are implemented as segment procedures.
The
remaining two are the data declaration and common
procedures of internal modules, and are implemented as
precompiled units.
In this section we will discuss the
purpose and implementation of each module.
Module EASYSTUFF contains all the data declarations and
common procedures for the internal modules except those
containing file references.
intrinsic unit.
advantages:
It is implemented as an
Intrinsic units 4 have two main
they are precompiled, and their code is
never actually put into the codefile of the user program.
So module EASYSTUFF saves both compile time and memory
space.
These are such great advantages that one might
like to put everything into an intrinsic unit.
However,
intrinsic units do not allow any file references.
Module FILESTUFF is implemented as a regular unit.
It
contains all the file declarations and common procedures
which use file references.
A regular unit 4 is
precompiled but the entire unit's code is actually placed
39
into the user program's codefile.
Because it will cause
a problem of stack overflow so we did not implement other
modules as regular units.
FILESTUFF refers to some of
the procedures of EASYSTUFF.
This is shown in Fig.
3.4.1 where these two modules are drawn with a connecting
line.
The following four internal modules are implemented as
segment procedures:
INTRODUC.
INITTRAC, GTRACE, PTRACE and
The code and data for a segment procedure 4
are in memory only when this procedure is activated.
By
implementing modules in this way, memory limitation
problems can be solved.
Module INTERFACE transfers the external procedure call
from the user program to an appropriate internal module.
The reason for that is to do the code overlay and to make
it easier for the user to use this language.
Fig.
shows a data flow diagram of module INTERFACE.
3.4.2
This
module is implemented as a set of short procedures, each
of which acts as an external procedure of Tracing
Language.
It transfers the control and data to an
appropriate internal module <segment procedure>.
TRACE.STUFF has 11 external procedures but Apple Pascal
only allows 7 segment procedures in a program 4 ,
external procedures must share the same segment
so some
40
External
Interface
Internal
Modules
Data
Declaration
i INITTRAC J-
-H
INTERFACE
I
t-
r-1 EASYSTUFF I
1
_jGTRACE
I
I
1
I PTRACE _II
~ I NTRODUC
Fig. 3.4.1
r-
~
t-
HFILESTUFFj
t--
Modular Design of TRACE.STUFF
41
..,.,-~-
t'
.......
__-.•_-•_e_J''""Io.l INITTRACE
~
p\
II
~i3
-jiNITTRAC
'\
2
--'--'"-
__.1_.-l, =NTRODUCTION
I
I
r/
:,;;,e, I
1-iTlWDUC
I
I
I
I
·_ ..... ~r
l-l•c:ACE
I
-----
/
../
...........
__
./
INTERFACE
--
/
/
42
procedure.
For instance, the external procedures
VSELECT, VRELEASE, ESELECT and ERELEASE share the
internal module GTRACE.
43
3.5
Errors prevention
One requirement for TRACE.STUFF is reliability; it is
accomplished by introducing variables to insure the
appropriate environment status of external procedure
calls.
The type, function and purpose of each status
variable are as follows:
Status variable ------- PRINTER
Type ------------------ BOOLEAN
Function -------------- to indicate whether or not a
printer is on line
Purpose --------------- to prevent the dead lock problem
when the program is requesting a
printer
value
meaning
TRUE
a printer is available
FALSE <default>
no printer is available
44
Status variable ------- COMPUTER
Type ------------------ CHARACTER
Function -------------- to indicate which model of APPLE
computer is being used
Purpose --------------- to select the proper printing
mode before transferring the
TEXT screen to a printer 7 • 8 •
This is necessary because for
different machines the TEXT
display is located in different
parts of memory11 • 6
(addresses
1024 through 3071 --- page 1 and
2, in an Apple II+, and 1024
through 2047 in an Apple IIe>.
meaning
value
• +.
'E'
using APPLE II+ or equivalent
(default>
using APPLE //e or equivalent
45
Status variable name -- !NIT
Type ------------------ BOOLEAN
Function -------------- to indicate the status of the
tracing mode
Purpose --------------- to prevent invalid calls of
ENDTRACE, TRACE, !TRACE, CTRACE
and RTRACE <as shown in Table
3.5.1)
value
meaning
TRUE
in the tracing mode
FALSE <default>
not in tracing mode
Status variable ------- SRAF
Type ------------------ BOOLEAN
Function -------------- to indicate whether or not a
graph is loaded into RAM
Purpose --------------- to prevent invalid calls of
VSELECT, VRELEASE, ESELECT and
ERELEASE (as shown in Table
3.5.1)
46
External
Procedure
Name
Valid Condition
Before Called
INIT
GRAF
Condition
After Called
INIT
GRAF
INTRODUCTION
F
-
F
-
INITTRACE
-
-
T
*
END TRACE
T
-
F
-
TRACE
T
-
T
-
I TRACE
T
-
T
-
RTRACE
T
-
T
-
CTRACE
T
-
T
-
VSELECT
-
T
-
T
VRELEASE
-
T
-
T
ESELECT
-
T
-
T
ERELEASE
-
T
-
T
-
*
don't care
user's option
Table 3.5.1
Status Checking of TRACE.STUFF
External Procedure Calls
47
value
meaning
TRUE
the data for graph is loaded
FALSE (default>
the data for graph is not loaded
Chapter 4
CAl GENERATOR --- CAI.WRITER
4.1 Hardware/Software Specification
CAI.WRITER was developed on an Apple //e microcomputer
system, and was tested on the Apple II+ and the Apple
1/e.
The hardware environment required for running CAI.WRITER
is:
• an Apple II microcomputer
• two disk drives
• a monitor
• a dot matrix printer <option>
The software needed for CAI.WRITER is a Pascal Operating
System, in which the SYSTEM.LIBRARY file must contain the
precompiled units TURTLEGRAPHICS, EASYSTUFF and
FILESTUFF.
The build-in unit TURTLEGRAPHICS provides
utility procedures for programming in graphic mode.
The units EASYSTUFF and FILESTUFF were implemented by
this author.
chapter 3.
Their design and purpose were discussed in
Appendix B shows the program listing of
units EASYSTUFF and FILESTUFF.
48
49
4.2 Input/Output Specification
Input to CAI.WRITER is a floppy diskette on disk drive 2
containing at least three files, SYSTEM.COMPILER,
SYSTEM.LINKER, and an algorithm TEXT file.
Algorithm
TEXT is a Pascal program with some restrictions.
First,
it must contain no compiler options and no USES clause.
Second, if a semicolon <;> is in a line of the algorithm
TEXT, it must be at the end of this line.
semicolon in a line is not allowed.
of the program is marked by
More than one
Third, the body part
I<* MAIN *>I.
Output of CAI.WRITER contains the three input files and
the following additional files (as shown in Fig.
4.2.1):
(1)
TEXT files of TRACE.STUFF declaration
(2)
DATA files of the graph photographs
(3)
DATA files of the graph data
(4)
DATA files of pieces of the algorithm
(5)
DATA file of the breakpoints of the algorithm
(6)
TEXT file of CAI
The first three types of files are copied from the master
diskette on disk driver 1.
Other files are generated
according to the algorithm TEXT file.
Follows describe
the files organization and their contents:
<1> TEXT files of TRACE.STUFF declaration
50
SYSTEI'!. CGMP I LER
SYSTEM. LINKER
Algorithm
•
•
•
TL Declaration
CAl
Piece of
Algorithm
Breakpoints
6raoh
Photograph
6raph Data
•
•
•
INPUT
OUTPUT
Fig. 4.2.1 Input/Output of CAI.WRITER
51
Each of these files contains part of the
declaration of TRACE.STUFF.
The contents of
these TEXT files are shown in Appendix B.
The
design of each file is discussed in chapter 3.
<2> DATA files of the graph photographs
When one of these files is read into RAM
starting at address 8192, it serves as the
photograph of a graph on the Apple GRAPH
screen.
They are binary files with the
following structure:
RECORD CASE BOOLEAN OF
TRUE :
<INTPART :
INTEGER>;
FALSE :
<PTRPART : AINTEGER>;
END
Such files have the advantage that the speed of
writing is faster than with other structures.
(3) DATA files of the graph data
Each graph is saved on two files, file of
ELIST and file of VLIST.
Arrays ELIST and
VLIST are discussed in section 3.3.
(4) DATA files of pieces of the algorithm
Structure of HALFPAGE is shown in section 3.3.
(5) DATA file of the breakpoints of the algorithm
52
Structure of BRKTBL is discussed in section
3.3.
(6) TEXT file of SCAI
This is a Pascal TEXT file, the content will
be discussed in section 4.3.
CAI.WRITER will asks the user for the names of the
algorithm file and tutorial files, this is the only
occurrence of user interaction in CAI.WRITER.
' .
53
4.3 Internal Design
CAI.WRITER contains two sub-modules PRODUCE and COPYFILE.
They are implemented as segment procedures.
Module
COPYFILE generates the files of TRACE.STUFF declarations,
graph photographs and graph data by copying some files
from the master diskette.
Module PRODUCE cuts the
algorithm file into small pieces, so each piece can fit
onto half of the screen.
PRODUCE also saves the
breakpoints in a file, and generates a CAI text file.
The process of generating a CAI text file involves:
<1>
Inclusion of the compiler option (*$S+*>.
This
option puts the SYSTEM.COMPILER in the swapping
mode, making more memory available for the
compile process.
(2)
Inclusion of the USES clause
USES TURTLEGRAPHICS, EASYSTUFF, FILESTUFF;
<3>
Insertion of the 'include directives' before the
first procedure/function declaration of the
algorithm:
(*$I#5:INITTRACE.TEXT*>
(*$I#5:GTRACE.TEXT*>
(*$1#5:PTRACE.TEXT*>
(*$i#5:INTERFACE.TEXT*>
"
54
The compiler option (*$filename*) tells the
SYSTEM.COMPILER to include another source file
called 'filename· in the compilation.
(4) Insertion of a call statement
INITTRACE (' filename ');
as the first statement of the main program.
where 'filename· is the file name of the
algorithm.
<5> Insertion of one of the call statements
TRACE ( ••••• >;
ITRACE <••••• >;
CTRACE <••••• >;
RTRACE <••••• >;
after each semicolon in the main program.
The
statement preceding the semicolon determines
which call statement is inserted.
For instance,
'ITRACE ( •••• >;'will be inserted if the
statement before the breakpoint is an assignment
statement for INTEGER.
<6>
Insertion of a call statement
ENDTRACE;
before the 'END. · clause.
'
Chapter 5
GRAPH EDITOR --- GRAPH.GEN
5.1 Requirements
GRAPH.GEN is designed to generate graphic data.
As
discussed in section 2.4, the graph will be represented
as a diagram, so the first requirement is that GRAPH.GEN
must be able to represent user input by means of drawing
the diagram.
As the data is input, part of the graph
diagram can be seen by the user.
Secondly, GRAPH.GEN must be able to detect allpossible
input errors.
Thirdly, to avoid redundant code the data structures of
graph in GRAPH.GEN must be compatible with those in
TRACE. STUFF.
55
56
5.2 Overall Design
GRAPH.GEN is a menu driven system; its main menu contains
four options:
Fig.
view, get, create and quit, as shown on
5.2.1.
When 'V' or '6' is chosen, GRAPH.GEN displays all the old
graph names to the user.
This allows the user to select
an old graph.
The process of
'create a new graph' contains the
following steps:
(1) locate each vertex
(2)
enter the cost of each edge
<3> enter a name for the new graph
In step(1) the user does not need to specify the x-,
y-coordinates of each vertex location, instead the arrow
keys are used to move the vertex to any position on the
screen.
This mode saves data entry time and allows the
user to make corrections easily.
shows this advantage.
Fig.
5.2.2 <a>-<e>
Some instructions are displayed on
top of the screen to inform the user of the proper
action.
In case of an input error, GRAPH.GEN will give
the user a beep and not accept the input.
For instance,
the user has no way to move a vertex off the screen.
57
GRAPH EDITOP
V
VIEW LIBRARY GRAPH
G
GET A LIBRARY GRAPH
N
EDIT A NEW GRAPH
(]
G!U IT
E!··.J TER
Fig. 5.2.1
'T'OUR CHO
ICE ---
The Main Menu of GRAPH.GEN
ENTER A VERTEX, CTRL-C FOR NONE
Fig.
(a)
Locating the Vertices
58
LOCATE VERTEX S BY ARROW KEYS
<SPACE> WHEN DONE
__
,
·=-
Fig.
(b)
Locating the Vertices
LOCATE VERTEX S BY ARROW KEYS
<SPACE> WHEN DONE
__
c-.
Fig.
5.2.2
(c)
Locating the Vertices
59
LOCATE VERTEX H BY ARROW KEYS
<SPAC~> WHEN DONE
H
D
(d)
Fig.
Locating The Vertices
LOCATE VERTEX H BY ARROW KEYS
<SPACE> WHEN DONE
c·
·-·
D
H
Fig.
(e)
Locating the vertices
60
Before going into step<2>, the screen displays all
vertices as shown on Fig.
5.2.3.
Each vertex
represented as a capital letter surrounded by a dotted
circle.
Step<2> accepts the names of the start vertex
and the end vertex for each of the edges, and accepts an
integer as the edge cost.
The input is checked one
character at a time, only a valid input will be accepted
and displayed.
Fig.
entering the edges.
5.2.4 (a)-(d) shows the process of
This is done by drawing one edge at
a time, so the user can see each edge being drawn on the
screen.
In the last step, GRAPH.GEN asks the user to input a file
name for the graph data, as shown on Fig.
5.2.5.
61
ENTER A VERTEX, CTRL-C FOR NONE
B
-
il
.
.
..L.'
.
A
H
~
.......
~-.a:
•.'""':""'
..:,:
(a)
Before Entering
the Edges
<EDGE)(COST)<SPACE>
Et-·-iTER
C TRL -C
~-~HEN
DONE
: B:
: G:
: D:
:A:
: H:
..... =-.
!-"'!ll
~
....,
~
.....J. ~- --·
(b}
Before Entering the Edges
62
Et-iTER
<EDGE)(COST)<SPACE>
C TPL -C l.-.fHEN DONE
.
.
: B:
·-·-·
.:::...1.
: D:
:A:
: H:
B~;
Fig.
=
5.2.4
Entering the Edges and Their Cost
(a)
<EDGE)<COST)<SPACE>
CTRL-C WHEN DONE
: B :······
: D:
-4···
....
·=- .
·-' .
:A:
: H:
Fig.
5.2.4
..
'
\OJ
Entering the Edges and Their Cost
63
<EIJ13E) <1::t:1E; T) <::=:PA•::E >
Ei--iTER
CTRL-C WHEN DONE
: D:
:A:
Fio. 5.2.4
(c)
Entering the Edges and Their Cost
(EDGE)<COST)<SPACE)
CTRL-C WHEN DONE
.9
-·4:-·-· ..
.. --·-··1..0 -·
2
. n
·-··
..L.."
-
•
:A:
-i
•-=<
...!...'"-'
i-lg.
5.2.4
=~OJ
~ntering
the Edges and
~ne1r
~os~
64
- ·=· .. ·.,...:. ·- .. -· -· -4 ... · :.·::. _·-: ..
.
s;;,
.
?i _.·
..
_.
•
"'!""\
•
.
.i..J
.
. H.
Fig.
(a)
Saving the Graph Data
.-,
.=:.
<8 FCF NO
.: .
...
--- ..--.
:=·H··.•t:.. ..!
. -.·
:A:
.
.
: H:
r~g.
5.2.5 (b)
Savinq the Graph Data
Chapter 6
CONCLUSION
6.1 Discussion
Appendix A shows some CAis generated by CAI.WRITER.
All
of these CAis were tested by SYSTEM.COMPILER, and the
subject codes did satisfy the requirements of SCAI
<section 2.2>.
Part of the output from these CAis is
included in Appendix A.
Helping the user to learn a subject is the goal of any
CAI package.
The SCAI model accomplishes this goal by
tutorial and simulation.
It has some important features:
<1> user interaction scheme
single letter user interaction commands
prompts help the user to use the
interaction commands easily
error detection mechanism
<2> selectable breakpoints
any set of algorithm breakpoints can be
selected by the user
editor type operations allow the user to
select the breakpoints easily
65
66
<3> double screens presentation
two screens are set by two segments of
physical memory, so the contents appearing on
the monitor can be switched from one screen
to another within 0.1 second
80 column screen to display the algorithm and
variable trace
192 x 280 high resolution screen to display
the diagram
<4> visible and reversible execution
algorithm is represented by PASCAL code, it
can be understood by junior students
the algorithm is automatic scrolling, so the
user can see which statement is in execution
the execution speed is controlled by the user
the execution can be backed up if needed
(5) hardcopy of trace
• the contents of the two screens can be
transferred to a printer
Using the preprocessor CAI.WRITER to generate the CAI
packages has some advantages:
<1> saves time
<2> reduces overhead of programming
67
(3) CAI package standardization
(4) the space for storing the CAI package can be
reduced since SCAI can be regenerated any time
The package was developed under the environment of Apple
UCSD Pascal, Table 6.1.1 lists some restrictions of Apple
Pascal/2/.
However, some nice features of UCSD Pascal
are employed in solving certain problems:
<1>
'Segment procedures' were used to overcome the
object code limitation <1200) and the program
size limitation.
<2>
'Include directive' solved the problem of large
text file in the editor.
(3)
'Pre-compiled unit' saved the compiler time.
Maximum size of
Procedure or function
Data chunk in a module
Characters in a string
Elements in a set
Segments per program
modules within a unit
Table 6.1.1
Apple Pascal Limitation
1200 bytes of object P-code
16,383 words per procedure
255 characters
512 elements
7 user segments
127 procedures or functions
The Restrictions of Apple Pascal
68
6.2 Further Improvements
Several possible improvements should be made:
1> We can improve the CAI.WRITER to release some
restriction on the input algorithm.
For instance, by
employing syntactic analysis, one can easily locate
the breakpoints of the algorithm and the beginning of
the main program.
2} One can extend TRACE.STUFF to include data types other
than graph, such as stack, queue and array.
3} CAI has many different modes, but the CAis generated
by CAI.WRITER contain only two modes, simulation and
tutorial.
One might like to modify TRACE.STUFF and
CAI.WRITER, to enable CAI.WRITER to generate a more
interesting CAI.
REFERENCE
1.
Brown, Marc H., 'Progress report: Brown university
Instructional Computing Laboratory· ACH SIGCSE
Bulletin 16, ~' 91-101 <February 1984>
2.
Lewis, T.G., Pascal Prograaaing Tor the Apple,
Prentice-Hall, 1981
3.
Aho, Alfred V., Hopcroft, John E., Ullman, Jeffrey
D., Data Structures and Algorithms, Addison-Wesley,
1983
4.
Apple Pascal Reference Hanual, Apple Computer Inc.,
1979
5.
Apple lie Reference Hanual, Apple Computer Inc.,
1982
6.
Apple lie Owner's Hanual, Apple Computer Inc., 1983
7.
Grappler+ Operators Hanual, Orange Micro Inc.,
1983
8.
RX Printer Operation Hanual, Epson Co., 1983
9.
Motil J., Programming Principles, Ridgeview
Publishing Co., 1981
10.
Foley, J.D., Dam, A.Van, Fundaaentals of Interactive
Computer Graphics, Addison-Wesley, 1982
69
Appendix A
EXAMPLES
ODDSQUARE Algorithm in Pascal ••.••••••••••••
71
ODDSQUARE.CAI Program <Generated by
CAl. WRITER>
72
Output of ODDSQUARE.CAI
73
Prim's MST Algorithm in Pascal
78
PRIM.CAI Program <Generated by CAI.WRITER> ••
80
PRIM.CAI Program <Modified Version> •••••••••
82
Output of PRIM.CAI •••.••••••••••••••••••••••
84
70
71
PROGRAM ODDSG;
(ffffttttttttttttttttittifif)
(t
i)
Algoritha ODDSQUARE
(t
S =N t N
(t
f)
f)
f)
(f
(ififfiftfffiiiffiiftifffiif)
VAR
N, 51 B, K: INTEGER;
BEGIN (t HAIN t)
WRITELN('INPUT N, PLEASE. 'l;
READLN!Nl;
s :=
0;
B : = 1;
FOR K :=
1 TO NDO
BEGIN
S := S + B;
B := B + 2;
END;
END.
72
0
(t$SH)
PROGRAM ODD5Q;
USES TURTLEGRAPHICS, EASYSTUFF, FILESTUFF;
(tftiffffffftffffffiffifffif)
t)
(f
(t
(t
Algorithm ODDSQUARE
S=NtN
(I
tl
tl
t)
(ttftftttfttftttttftftfttfft)
VAR
N, 51 B, K: INTEGER;
(t$li4:1NTRODUC.TEXTtl
(t$li4:INITTRACE.TEXT+l
(t$li4:GTRACE.TEXTtl
(t$114:PTRACE.TEXTtl
(t$li4:INTERFACE. TEXTtl
INITTRACE!'t5:0DD5Q'l;
BEGIN (t MAIN tl
TRACE!2l;
WRITELN! 'INPUT N, PLEASE. 'l;
TRACE!3l;
READLN!Nl;
5 := 0;
ITRACEI4,5l;
B := 1j
ITRACE!5,Bl;
FOR K := 1 TO NDO
BEGIN
5 : = 5 + B;
ITRACE!6,5J;
B := B + 2;
ITRACEU,Bl;
END;
TRACE!Bi;
END TRACE;
END.
'
73
BESIN (* MAIN tl
wR!TEUH 'INPUT N, PLEASE. 'i;
READLN (N); 3
s := 0; 0
B := 1;
FOR K := 1 TO
INPUT N, PLEASE.
NDO
BE SIN
S : = S + B~
B : = B + 2;
END;
END.
Tracing: N>ext B>ackup T>ext B>raph E>nd P>rint Q)uit
74
BEGIN (i MAIN f)
WRITEUH' INPUT N, PLEASE. 'l;
INPUT N, PLEASE.
F:EADLN(Nl; 3
: : .= i"i•
(1
•••
B := 1;
1
....
&
••• ,
FOR K := 1 TO N DO
BEGIN
S:=S+B;
B := B + 2;
END;
END.
Tracing:
N>ext
B>ackup
T>ext
G>raph E>nd
P>rint
i;)}uit
75
BE5IN (f ~AIN f)
WRITELN('INPUT N, PLEASE. 'J; INPUT N, PLEASE.
READLN{N); 3
0
B := !; 1
FuR K := 1 TO
s := 0;
N DO
BEGIN
S := S + B;
B := B + 2;
3
END:
END.
Tracing:
N>ext B>ackup Dext E>raph E>nd P>rint IDuit
76
4R1TEL~(
INPUT
: : = ·.·•
5 := B
CPT'.~
O...iH.i•
~ND.
N~ PLE~SE.
! !
iNPUT
~.
PLEASE.
77
BEGIN
MAIN
\t
f)
WR!TELN( INPUT N, PLEASE.
I
F:EADLN!NJ:
):
INPUT N. PLEASE.
•'
B ; :: 1~
·UK \ := I !D N DD
BEC!N
S : = 3 + B: 9
B : = E + 2; -:
tf-tV;
Tracing: N>ext B>acKup T>ext G>rapn E>nd P>r1rt D>uit
78
PROGRAM PRIM;
CONST
KAXN = 12;
INFINITY = 9999.0;
TYPE
COST= PACKED ARRAY [1 .. 11AXN 1 1.. 11AXNJ OF REAL;
VAR
TEMP : INTEGER;
C : COST;
LDWCDST : PACKED ARRAY [1 •• 11AXNJ OF REAL;
CLOSEST : PACKED ARRAY [1 •• 11AXNl OF INTEGER;
N, I, J 1 K: INTEGER;
KIN : REAL;
CH : CHAR;
PROCEDURE ENTERDATA;
ll BUILD THE COST MATRIX C l)
VAR
111 1112 : INTEGER;
BEGIN
N:= V[OJ. Y;
FOR I := 1 TO NDO
FOR J := 1 TO NDO
C[I,Jl := INFINITY-1;
FOR I := 1 TO E[OJ.COST DO
BEGIN
111 := SEARCH!E[ll.V11;
112 := SEARCH!E[Il.V2l;
C[I11,M2J := E[ll.COST;
C[l12 1111l := E[IJ.COST;
END;
END; (l ENTERDATA I)
BEGIN (l MAIN ll
ENTERDATA;
FOR I := 2 TO NDO
BEGIN
LOWCOST£11 := C£1,11;
CLOSEST[!] := 1;
END;
FOR I := 2 TO NDO
BEGIN
KIN := LOWCOST£Il;
K := I;
FOR J := 2 TO NDO
IF lLOWCOST[J] < MINI AND
<J <> Il
THEN
BEGIN
KIN := LOWCOST[Jl;
79
K := J;
END;
LOWCOST£Kl := INFINITY;
FOR J := 2 TO NDO
IF IC£K,Jl < LOWCOST[Jll AND
ILOWCOST[JJ < INFINITY> THEN
BEGIN
LOWCOST[Jl := C£K,Jl;
CLOSEST£Jl := K;
END;
END;
END.
80
(i$5ttl
PROSRAH PRIM;
USES TURTLE6RAPHICS 1 EASYSTUFF, FILESTUFF;
CONST
I'IAXN = 12;
INFINITY = 9999.0;
TYPE
COST= PACKED ARRAY £1 •• 11AXN,1 •• 11AXNl OF REAL;
VAR
TEI1P : INTESER;
C : COST;
LONCOST: PACKED ARRAY [1 •• 11AXNl OF REAL;
CLOSEST : PACKED ARRAY £1 •• 11AXNl OF INTESER;
N, I, J, K: INTESER;
11IN : REAL;
CH : CHAR;
(t$134:INTRODUC.TEXTtl
(t$li4:INITTRACE.TEXTtl
(t$1#4:6TRACE.TEXTtl
(t$li4:PTRACE.TEXTfl
(t$1#4:INTERFACE.TEXTtl
PROCEDURE ENTERDATA;
(t BUILD THE COST MATRIX C f)
VAR
111,112 : INTESER;
BESIN
N := V£0]. Y;
FOR I := 1 TO NDO
FOR J := 1 TO N DO
C£I,Jl := INFINITY-1;
FOR I := 1 TO E£0l.COST DO
BESIN
111 := SEARCH<E£Il.Vll;
112 := SEARCH<E£IJ.V2l;
C£111 11121 := E£Il.COST;
C£M2,M1l := E£IJ.COST;
END;
END; (f ENTERDATA f)
INITTRACEl'I5:PRIH'l;
BESIN (t MAIN t)
ENTERDATA;
TRACE i2l;
FOR I := 2 TO NDO
BESIN
LOWCOST£11 := C£1 1 11;
RTRACE<3,LONCOST£Ill;
CLOSEST£!] := 1;
ITRACE<4,CLOSEST£Ill;
81
END;
TRACE 15l;
FOR I := 2 TO NDO
BEGIN
"IN := LOWCOST[ll;
RTRACEib,"IMl;
K := I;
!TRACE <7 1Kl;
FOR J := 2 TO N DO
IF ILOWCOST[Jl < "INl AND
IJ 0 I>
THEM
BEGIN
"IN := LOWCOST[JJ;
RTRACE IB,IHNl;
K := J;
ITRACEI!f,Kl;
END;
TRACE <10>;
LOWCOST[Kl
:=
INFINITY;
RTRACE!ll,LOWCOST[Kll;
FOR J := 2 TO NDO
IF (C[K,Jl < LOWCOST[Jll AND
ILOWCOST[J] < INFINITY> THEN
BEGIN
LOWCOST[Jl := C£K,Jl;
RTRACE!12,LOWCOST£Jll;
CLOSEST[Jl := K;
ITRACEI13,CLOSEST[Jll;
END;
TRACE <14>;
END;
TRACE I 15);
END TRACE;
END.
82
(t$SH)
PROGRAM PRIM;
USES TURTLEGRAPHICS, EASYSTUFF, FILESTUFF;
CONST
HAUl = 12;
INFINITY = 9999.0;
TYPE
COST= PACKED ARRAY [l •• ftAXN,l •• MAlftl
Df
REAL;
VAR
TEI'IP : INTEGER;
C : COST;
LOWCOST : PACKED ARRAY [1 •• MAXNl OF REAL;
CLOSEST : PACKED ARRAY [l •• MAXNl OF INTEGER;
N, I, J, K: INTEGER;
I'IIN : REAL;
CH : CHAR;
!t$II4:INTRODUC.TEXTt)
!t$II4:INITTRACE.TEXTtl
!t$li4:STRACE.TEXTtl
!t$II4:PTRACE.TEXTtl
!t$li4:1NTERFACE.TEXTtl
PROCEDURE ENTERDATA;
!t BUILD THE COST "ATRIX C t)
VAR
l'll,M2 : INTEGER;
BEGIN
N := V[Ol. Y;
FOR I := 1 TO N DO
FOR J := 1 TO NDO
C[I,Jl := INFINITY-1;
FOR I := 1 TO E[OJ.COST DO
BEGIN
Ml := SEARCH!E[IJ.Vll;
M2 := SEARCH!E£IJ.V2J;
C[Ml,M2J := E£IJ.COST;
C£M2,Mll := E£Il.COST;
END;
END; (t ENTERDATA tJ
BEGIN (t MAIN
ENTERDATA;
INITTRACE!'I5:PRIM'J;
t)
TRACE!2l;
FOR I := 2 TO NDO
BEGIN
LOWCOST[IJ := C£1,11;
RTRACE!3,LOWCOST[IJJ;
CLOSEST£!] := 1;
ITRACE!4,CLOSEST£IJ>;
83
END;
VSELECT!V[lJ.NAKEl;
TRACE!Sl;
FOR I := 2 TO NDO
BESIN
KIN := LOWCOST[lJ;
RTRACE!b 1 KINl;
K := I;
FOR J := 2 TO NDO
IF !LOWCOST[JJ < KlNl AND
!J 0 ll
THEN
BESIN
KIN := LOWCOST[JJ;
RTRACE!8 1tliNl;
K := J;
ITRACE 19 1Kl;
END;
TRACE !10);
ESELECT!V[KJ.NAtlE 1V[CLOSEST£Kll.NAKEl;
VSELECT!V[Kl.NAtlEl;
LOWCOST[Kl := INFINITY;
RTRACE!ll,LOWCOST[KJl;
FOR J := 2 TO NDO
IF !C[K,JJ < LOWCOST[JJl AND
!LOWCOST[Jl < INFINITY! THEN
BESIN
LOWCOST[Jl := C[K 1JJ;
RTRACE!l2 1LOWCOST[Jll;
CLOSEST[Jl := K;
ITRACE!l3 1 CLOSE5T[Jll;
END;
TRACE I14l;
END;
TRACE I15l;
END TRACE;
END.
84
; A __:
-
--
l
-- _.-6
:_ -~--~---------s-------- :~
·c ·:---------s--------==--~ -_:
_____ 6--
=~.,.
.....
·c...;- __ _
-~.\_
;i
. _. .
~
. ._
: E :-----------6-·--------: F:
Snapshot I 0
--
_.-6
---
Original
_.--0-.
_
i -----s ..__
:_-~.>-------s--------:-
·c:--------5·-------: =--~ _:
.
··-.
'lo
..
:- .... ·.
_.·
: . E . :----·····--6---·-··---: - F:.
After selecting vertex A
Snapshot I
-
.....6········7········s.
:
---~-----------5--------:
-_I_-
-
.
:--------5·-----------~-. --~ ... ·...
..
-
~--
______ 6--
... . _. ·
c
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Snapshot I 2
After selecting edge CA
9
85
_.··., .. ········6
. . . . C?··
.
.
A.
s ........._.·· ..
--~.. ---·······5·······-~v-······5·········=--~--
,__~
.....6.......
' ·'4·...
;/
' - _. ·
·_... -·.
: . E . :···········6·········-: . F -:
Snapshot I 3
After selecting vertex C
.... ·~··· ..
rh.
.
:
:
:
.
:
·
:
:
D:
----..-{,
:: ii:; :: ::::·.·: ..
. -.....
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.....
~-
...6
"'o
•
"'4
!2
-·~- .._.:··
_ ....
: .. E . :···········6·········-: . F .. :
Snapshot I 4
After selecting edge FC
(A-
···f
G
.·· ...........6······
.
·······s .......... ··.
....""'
:
..
..
. . B . :········5········ ~--·····5········. . D . .
. -...
.
...-- -
\3
......
. ·····
......6
..
-:;;!....
4~_.....
::~~:·;··········6·········· ~
Snapshot I 5
After selecting vertex F
•
86
_ . . G·········d ·········s ......
.n ·:
:... :B .-~---~: ..... 5········
c)·······5······:·:: ·. .
.. ······~..4
/""
·-.....3
·.
I
~
..6
....~ ..·····
~:E:·-·········6··········®
Snapshot I 6
After selecting edge DF
.. · . 01 . · .
. ···., .......... 6···
0
6....... . . . . 4
.
·. B . .-········5········
. -..
\~
.·..
.~ ..·· ..··
.
····s .........
~
c ·······5········CD)
/.-
2
I
' >-----
~
:_E_:-··········6··········(~
Snapshot I 7
After selecting vertex D
,..-.....
..... ··J'T)·....... .
~
·· ........... 6
:~.'
5 ........ ~~
5~······5····-:;~
....~
v
6 ..· · · · · · , 4
··:·~.........
z
: ..~.:-··········6··········"~
Snapshot I 8
After selecting edge BC
87
········.s ..
.. 6 ___...-··
~----0-······5··:::::·@
-~-
,4):6I
. . _. ·
.6.....
-"' ...··
: E :···········6··········
Snapshot I 9
F
After selecting vertex B
r;;~
..
····-~·- ...
1
_..6···
····s ..
~----0--····5·::::::-0
\
~
\ ._........
E;.··
' '4
.··
~
~
-,r/
: . E ~ :-··········6·······-··(F"'\
..;_/
Snapshot I 10
.... 6·········
After selecting edge EB
C?
.
·········s ...
~----0-······5···:::::@
\
:3
F
..··.....
6.·
.· ,
.....4
-. . .>-<I
I
.
~.'l······ ····6 ······· ···( F I
.....~
........~
Snapshot I 11
After selecting vertex E
Appendix B
PROGRAM LISTING
Program GENERATOR ••••••••••••••••••••••••••
89
Unit EASYSTUFF
91
Unit FILESTUFF
96
Unit GUNIT ••••••••••••••••••••••••••••••••• 101
. . . . .. .. . . . . . . . . .
GET GRAPH . . . . . . . . . . . . . . . . .
INTRODUC . . . . . . . . . . . . . . . . .
INITTRACE . . . . . . . . . . . . . . . .
GTRACE . . . . . . . . . . . . . . . . . . .
PTRACE . . . . . . . . . . . . . . . . . . .
Segment Procedure GET TABLE
102
Segment Procedure
106
Segment Procedure
Segment Procedure
Segment Procedure
Segment Procedure
112
114
118
123
Module INTERFACE .•••••••••••••••••••••••••• 127
88
89
(f$SHl
(fffltttfffffflfftffffttffftffftffftftttffffffflflf)
(I
(I
(I
(I
(I
(I
(I
f)
ACAI package generator
Apple 1/e Version 3.1
California State University, Northridge
Karch 1984
By Shi-Chung Liu
f)
f)
f)
f)
f)
I)
(fftllltffllfltttlffflffffflffffflfffffffffffffffff)
PROGRAM GENERATOR;
USES
TURTLESRAPHICS, EASYSTUFF, SUNil, FILESTUFF;
VAR
PNAI'IE : 11ESG;
(1----------------------------------------1)
lt$li5:SETTABLE.TEXTtl
(1----------------------------------------f)
(t$II4:STRACE.TEXTtl
(f----------------------------------------1)
lt$li5:GETGRAPH.TEXT1l
(1---------------------------------------------------------------------------f)
BEGIN It GENERATOR tl
ONLINE := TRUE;
GRAF := TRUE;
PAGE !OUTPUT> ;
WRITEIATI5,10l, '11 AN U'l;
WRITEIATI8,3l, 'P GENERATE TRACING PACKAGE' I;
WRITEIATi10,3l, 'G GENERATE GRAPH'l;
WRITEIATI20,0l, 'ENTER P or 6 FOR YOUR CHOICE 'l;
CASE CHARREAD!['P', 'Q', 'G'll OF
'P' : BEGIN
PAGE !OUTPUT> ;
WRITEIATI5,10l, 'GENERATE TRACING PACKASE'l;
WRITEIATIS,12l, 'WHERE IS YOUR ALGORITHM TEXT FILE ?'l;
READLNIPNAKEl;
6ETTABLEIPNAI1El;
END;
90
'6' : 6ET6RAPH;
END;
END. (I GENERATOR I)
(t--------------------------------------------------------------------------tl
91
(t$S+tl
UNIT EASYSTUFF; INTRINSIC CODE 25 DATA 2b;
INTERFACE
USES
TURTLESRAPHICS;
CONST
SIZETABLE = 29;
SIZEBUFFER = 29;
TYPE
CHARSET = SET OF CHAR;
HESS = STRINS£801;
VERTEX = RECORD
NAIIE : CHAR;
X,Y: INTEGER;
END;
VLIST =PACKED ARRAY£0 •• 121 OF VERTEX;
EDSE = RECORD
V1 1 V2 : CHAR;
COST : INTEGER;
END;
ELIST =PACKED ARRAY£0 .• 151 OF EDSE;
BRK = RECORD
PASENO : STRINS£11;
LINENO : INTEGER;
END;
BRKTBL =PACKED ARRAY [O •• SIZETABLEJ OF BRK;
HALFPASE =PACKED ARRAY£1 .• 111 OF IIESS;
SHORT = STRINS£101;
BUF = RECORD
Tl : INTEGER;
STRI : SHORT;
STOP : BOOLEAN;
END;
BUFR =PACKED ARRAY£0 •• SIZEBUFFERl OF BUF;
VAR
PROMPT : INTEGER;
BUFFER : BUFR;
PASEID,LAST,TOP,BOTTOII : STRINS£11;
NONSTOP, ENDINS : BOOLEAN;
HEAD,TAIL,CURRENT : INTEGER;
NAI'IE : HESS;
V: VLIST;
E : ELIST;
ONLINE, SRAF, INIT : BOOLEAN;
COIIPUTER : CHAR;
PROCEDURE I'IESSA6E(X 1
92
Y : INTEGER;
L : I'IESSl; (I WRITE ASTRING L START AT IX, Y> OF
6RAFI'IODE SCREEN tl
PROCEDURE PLOTCHARIX,Y : INTEGER; CH : CHARI;
PROCEDURE BELL;
FUNCTION ATIX,Y:INTEGERl:CHAR;
FUNCTION CLEAR:CHAR;
FUNCTION SUBCLEAR:CHAR;
FUNCTION CHARREADIVS:CHARSETl:CHAR;
FUNCTION SEARCHICH : CHARI : INTEGER;
FUNCTION EINDEXIC1,C2 : CHARl:INTEGER;
PROCEDURE PI'IT1;
PROCEDURE INCIVAR J : INTEGER!;
PROCEDURE DECIVAR
J :
INTEGER!;
IHPLEHENTATION
(1----------------------------------------f)
PROCEDURE BELL;
BEGIN
WRITE ICHR 17l l;
END;
(1----------------------------------------f)
FUNCTION AT;
BEGIN
GOTOXYIY,Xl;
AT := CHRIOl;
END;
(1----------------------------------------i)
FUNCTION CLEAR;
BEGIN
CLEAR := CHR126l;
END;
93
(i----------------------------------------1)
FUNCTION SUBCLEAR;
BEGIN
SUBCLEAR := CHRI29l;
END;
(1----------------------------------------f)
FUNCTION CHARREAD;
VAR
C : CHAR;
BEGIN
READIKEYBOARD,Cl;
MHILE NOT (C IN VSl DO
BEGIN
BELL;
READIKEYBOARD,Cl;
END;
CHARREAD := C;
END;
(1----------------------------------------f)
PROCEDURE HESSASE;
BEGIN
PENCOLOR!NONE>;
HOVETO (X I Yl j
PENCOLORIWHITE>;
WSTRING!Ll;
END;
(1----------------------------------------f)
PROCEDURE PLOTCHAR;
BEGIN
PENCOLORINONE>;
HOVETOtx,Yl;
PENCOLORIWHITEl;
WCHARICHl;
END;
(1----------------------------------------f)
FUNCTION SEARCH;
VAR
I : INTEGER;
BEGIN
I : = 1;
MHILE IJ[IJ.NAHE () CH DO
I := I + 1;
SEARCH := I;
END;
94
(1----------------------------------------t)
FUNCTION EINDEX;
VAR
I : INTESER;
FOUND : BOOLEAN;
BESIN
FOUND := FALSE;
I := 1;
WHILE II <= E[OJ.COSTl AND INOT FOUNDl DO
IF IE[Il.Vl = Cll AND IE£Il.V2 = C2l THEN
FOUND := TRUE
ELSE
I:=l+l;
IF FOUND THEN
EINDEX := I
ELSE
EINDEX := 0;
END;
(1----------------------------------------t)
PROCEDURE P11Tl;
BESIN
WRITEIATI23 10l 1 CLEAR>;
IF PROMPT = 1 THEN
WRITEI'Select Breakpoints: U>p D>own S>elect F>ree P>rint Q}uit'l
ELSE
WRITEI'Tracing: N>ext B>ackup T>ext S>raph E>nd P>rint Q)uit'l;
END;
(1----------------------------------------1)
PROCEDURE INC;
BE SIN
IF J = SIZEBUFFER THEN
J := 0
ELSE
J:=J+l;
END;
(1----------------------------------------t)
PROCEDURE DEC;
BESIN
IF J = 0 THEN
J : = SIZEBUFFER
ELSE
J:=J-1;
END;
(t----------------------------------------1)
95
BESIN
NONSTOP := FALSE;
ENDINS := FALSE;
COMPUTER := 'E';
ONLINE := FALSE;
SRAF := FALSE;
HHT : = FALSE;
END.
96
(I$SHl
UNIT FILESTUFF;
INTERFACE
USES
TURTLESRAPHICS, EASYSTUFF;
TYPE
HFPS = FILE OF HALFPASE;
VAR
TABLE : FILE OF BRKTBL;
H,Hl : HFPG;
Z9X22PRINT : TEXT;
Z9X22F : FILE;
FV : FILE OF VLIST;
FE : FILE OF ELIST;
SNAP : INTEGER;
PROCEDURE PLOT;
(I
PLOT THE SRAFHODE SCREEN TO THE
PRINTER t)
PROCEDURE NOTEE <A : HESS; Cl,C2 : CHAR>;
PROCEDURE PRINTING;
PROCEDURE BLOADIFNAHE:CHARl; It SET THE PICTURE FROM FNAHE
PROCEDURE BSAVEIFNAHE:CHARl;
(t
SAVE THE SRAFHODE SCREEN ON FNAHE tl
PROCEDURE GETVEIA : CHAR>;
PROCEDURE PRINTIA:HESS; LOC:INTESERl;
PROCEDURE CHECKHEHORYII:INTESER>;
PROCEDURE CHECKBOTTOHII:INTESER>;
PROCEDURE CHECKTOP!l:lNTESERl;
IMPLEMENTATION
TYPE
DISKBLOCK = RECORD CASE BOOLEAN OF
TRUE: IINTPART:INTESER>;
FALSE: IPTRPART:AINTESERl;
END;
VAR
I)
97
DB : DISKBLOCK;
IO : INTEGER;
(1----------------------------------------f}
PROCEDURE PLOT;
BEGIN
IF ONLINE THEN
BEGIN
"ESSASEIO,lBO,'
'l;
REWRITEIZ9X22PRINT, 'PRINTER: 'l;
WRITELNIZ9X22PRINT,CHRI25) 1 'G' 1 'E'l;
CLOSEIZ9X22PRINT>;
SNAP := SNAP + 1;
nESSAGEIO,lBO, 'Coamand: N B T G E P G'l;
END;
END;
(1----------------------------------------f)
PROCEDURE NOTEE;
BEGIN
IF ONLINE THEN
BEGIN
CLOSE IOUTPUTl ;
REWRITEIOUTPUT, 'PRINTER: 'l;
WRITE I'
WRITELNISNAP:3,' ',A,Cl,C2l;
WRITELN;
CLOSEIOUTPUT>;
REWRITEIOUTPUT, 'CONSOLE:');
END;
END;
Snapshot
I' l ;
(1----------------------------------------1)
PROCEDURE PRINTING;
BEGIN
IF ONLINE THEN
BEGIN
REWRITEIZ9X22PRINT, 'PRINTER: 'l;
IF CO"PUTER = 'E' THEN
WRITELNIZ9X22PRINT 1 CHRI25) 1 '30L' 1CHRI25l, 'A' 1 CHRI25l, '8' 1 'S')
ELSE
WRITELNIZ9X22PRINT,CHRt25) 1 '2', 'S'l;
CLOSEtZ9X22PRINTl;
END;
END;
(t----------------------------------------1)
PROCEDURE BLOAD;
VAR
98
F : STRINSUl;
BEGIN
DB.INTPART := 8192;
F := • ';
F£1 l := FNAI1E;
RESETIZ9X22F,CONCATt'I5:6RAPH' ,F, '.FOTO'll;
IO : = BLOCKREAD IZ9X22F ,DB. PTRPARY, lbl;
CLOSEIZ9X22F 1 LOCKl;
END;
(t----------------------------------------1)
PROCEDURE BSAVE;
VAR
F : STRINS£11;
BEGIN
DB.INTPART := 8192;
.-
F ·- •••
'
F[ ll : = FNAI1E;
REWRITEIZ9X22F,CONCATI'I5:6RAPH' ,F, '.FOTO'll;
10 := BLOCKWRITEIZ9X22F,DB.PTRPARTA 1 1bl;
CLOSEIZ9X22F,LOCKl;
END;
(t----------------------------------------1)
PROCEDURE SETVE;
VAR
I : INTEGER;
F : STRINS[ll;
BESIN
!t SETVE
F ·-- •••'
FUl := A;
.
tl
RESETIFV,CONCATI'IS:SRAPH' ,F,' .VLIST'll;
SETIFVl;
FOR I := 0 TO FVA(OJ.X DO
BEGIN
V£Il.NAI1E := FVA£Il.NAI1E;
V[IJ.X := FVA[Jl.X;
V[Il.Y := FVA[ll.Y;
END;
ClOSEIFV,LOCKl;
RESETIFE,CONCATt'IS:SRAPH' ,F, '.ELIST'll;
SETtFEl;
FOR I := 0 TO FEA[Ol.COST DO
BESIN
E£Il.V1 := FEA[Jl.Vl;
E£Il.V2 := FEA£Il.V2;
E£Il.COST := FEA[Il.COST;
END;
99
CLOSEIFE,LOCKl;
END; (I GETVE I)
(1----------------------------------------1}
PROCEDURE PRINT;
VAR
I : INTEGER;
BEGIN
RESET!Hl,Al;
GET!Hll;
IF LOC = 3 THEN
BEGIN
NRITEIATI23,0l,CLEAR,ATI22,0l,CLEARl;
FOR I := 1 TO 11 DO
NRITELNIH1A[lll;
WRITELN;
END
ELSE
FOR I := 0 TO 10 DO
NRITEIAT<ILOC-ll1ll+I 10l 1 CLEAR,H1A(l+1Jl;
CLOSEIHl,LOCKl;
PHTl;
END;
(t----------------------------------------1)
PROCEDURE CHECKHEHORY;
BEGIN
IF PASEID <> TABLE'·[Il.PAGENO THEN
BEGIN
CLOSEIH,LOCKl;
RENRITElH,CONCATINAHE, '. ',PAGEIDll;
PUT!Hl;
CLOSEIH,LOCKl;
RESETIH,CONCATINAHE, ', ',TABLEA[JJ.PA6ENOll;
GET!Hl;
PAGEID := TABLEA[Jl.PAGENO;
END;
END;
(t----------------------------------------1)
PROCEDURE CHECKBOTTOH;
BEGIN
WHILE TABLEA£Il.PASENO > BOTTOH DO
BEGIN
TOP := BOTT011;
BOTTOH[1l := SUCCITOP[1Jl;
PRINTICONCATINAHE,'.' 1BOTTOHl 13l;
END;
END;
100
(f----------------------------------------1)
PROCEDURE CHECKTOP;
BEGIN
IF TABLEh[lJ.PAGENO < TOP THEN
BEGIN
TOP := TABLEh£IJ.PASENO;
BOTTOn£1) := SUCC!TOP£1Jl;
PRINT!CONCAT!NAnE,'. ',BOTTOnl,2l;
PRINT!CONCAT!NAME, ·• ',TOPl,1l;
END;
END;
{f----------------------------------------1)
BEGIN
SNAP := -1;
END.
101
(t$SHI
UNIT SUNIT; INTRINSIC CODE 27;
INTERFACE
USES
TURTLESRAPHICS, EASYSTUFF;
FUNCTION HELPIVNAHE : HESSI : CHAR;
PROCEDURE QUESTIONILOC : INTESER; NORD : HESS;
VAR NAME : HESSI;
IHPLE11ENTATION
(1----------------------------------------t)
FUNCTION HELP;
BEGIN
WRITEIATI0 101 1 CLEAR 1 'Variable ',VNAHE,. is type of'l;
WRITE IATll 1 51 1CLEAR 1 'Dnteger ',AT 12,51 ,CLEAR 1 'R)eal 'l;
NRITEIATI3 15l,CLEAR,'C)har' 1 ATI4 15l ,CLEAR, 'O>thers'l;
WRITEIATI5 1 0l ,CLEAR,'Help 1e 1 please ! 'I;
WRITEIATtb,Ol,CLEAR, '--------------------------------------------------'1;
WRITE!'-------------------· 1ATI5,1811;
HELP:= CHARREAD(['l' ,'R' I '0' I 'C'Jl;
WRITEt'Thank you. 'I;
END; It HELP t)
(1----------------------------------------f)
PROCEDURE QUESTION;
BE6IN
WRITEIATILOC,OI, 'DO YOU WANT SAY SOHETHINS IN THE 'I;
WRITEIWORD,' OF THE PACKASE ?'I;
WRITEIATILDC+l 1 101 1 'Y/N'l;
IF CHARREADt£'Y' 1 'N'JI = ·y· THEN
BESIN
WRITEIATILOC+2 1 5l, 'WHERE IS THE TEXT FILE ?'l;
READLNINAHEI;
END
ELSE
NAME := 'UU';
END;
END;
(t----------------------------------------1)
BE6Hl
END.
102
(t
IS:SETTABLE.TEXT
t)
(1-------------------------------------------------------------------------i)
SESKENT PROCEDURE SETTABLEINAKE : KESSl;
VAR
L : STRINS£11;
I,J,K 1N: INTEGER;
Y: KESS;
CAl : TEXT;
TAB : KESS;
INTROl, INTR02 : KESS;
{i----------------------------------------1)
SEGMENT PROCEDURE DECLPART;
VAR
FOUND : BOOLEAN;
(1--------------------------i)
PROCEDURE INCLUDE;
BEGIN
WRITELNICAI,CONCATITAB,' l1$li4:1NTRODUC.TEXT1l'll;
WRITELNICAI,CONCAT!TAB, '(1$II4:INITTRACE.TEXT1l'll;
WRITELNICAI,CONCATITAB, '(1$li4:6TRACE.TEXTtl'll;
WRITELNICAI,CONCATITAB, '(t$II4:PTRACE.TEXTtl'll;
WRITELN!CAI,CONCATITAB, '(1$II4:1NTERFACE.TEXT1l 'll;
END;
(1--------------------------1)
BEGIN
FOUND := FALSE;
WRITELNICAI,CONCAT!TAB, '(t$S+Il 'll;
READLNIZ9X22PRINT,Yl;
WHILE <NOT EOFIZ9X22PRINTll AND
<POSI'(I MAIN t)' ,Yl =Ol AND
!POSI'!tMAINtl' ,Yl = Ol
DO
BEGIN
WRITELNIATI23 10l 1 Yl;
IF IIPOS!'PROCEDURE ' 1 Yl > Ol DR IPDSI'FUNCTIDN ' 1 Yl > Oll AND
!NOT FOUND)
THEN
BEGIN
FOUND := TRUE;
INCLUDE;
END;
WRITELN !CAl, Yl;
IF I POSI'PROSRAM ',Yl > 0 l AND
I POS!'; ' 1 Yl > 0 l
THEN
WRITELNICAI,CONCATITAB, 'USES TURTLESRAPHICS, EASYSTUFF 1 FILESTUFF; 'll;
103
READLN<Z9X22PRINT,Yl;
END;
IF NOT FOUND THEN
INCLUDE;
END; (I DECLPART t)
(1----------------------------------------f)
SEGMENT PROCEDURE TLCOPY!Y:HESS; I:INTEGERJ;
VAR
J,K : INTEGER;
VNAHE : HESS;
CH : CHAR;
INT,TL : HESS;
DONE : BOOLEAN;
BEGIN
DONE := FALSE;
J := POS!':=' ,Y>;
STR!I,INT>;
IF J > 0 THEN
BE SIN
VNAHE := COPY!Y,l,J-1>;
NHILE VNAHE[LENSTH!VNAHEJJ = ' ' DO
VNAHE := COPY!VNAHE,l,LENSTH!VNAHEJ-ll;
NHILE POSt' ',VNAHEJ > 0 DO
VNAHE := COPY!VNAHE 1 21 LENSTH!VNAHEJ-ll;
CH := HELP!VNAHEJ;
IF CH <> '0' THEN
BEGIN
TL := ' ';
TL£11 : = CH;
TL := CONCAT!TL, 'TRACE(' ,INT,' 1 ' ,VNAHE, 'J;'l;
DONE := TRUE;
END;
END;
IF NOT DONE THEN
TL := CONCAT<'TRACE!' 1 INT,'l;'l;
NRITELN!CAI,CONCAT!TAB,TL>J;
END; (I TLCOPY I)
(1----------------------------------------t)
SEGMENT PROCEDURE HAINPART;
VAR
Y2 1 Yl : HESS;
MAIN, HAINl : BOOLEAN;
BEGIN
Yl := Y;
IF INTROl <> '$$$$' THEN
Y2 := CONCAT< 'INTRODUCTION (' " 1 INTROl," 'l; 'l
ELSE
104
Y2 := ";
Y:= CONCAT IY, HtB, Y2 1 'IN ITT RACE I'" ,NAI'IE," 'I;' I;
HAIN := TRUE;
WRITELNIATI23,0I,Yll;
WHILE NOT EOF!Z9X22PRINTI DO
BEGIN
I : = 1;
J:=J+l;
.- '
L ·-
I
'•
L£11 := CHRIJ+b41;
REWRITE!H,CONCAT!NAI'IE, '. ',Lll;
WHILE !NOT EOF!Z9X22PRINTll AND II <= 111 DO
BEGIN
IF !'lAIN THEN
BEGIN
!'lAIN := FALSE;
H''[IJ := Yl;
END
ELSE
H"[IJ := Y;
IF POSI';',Yl > 0 THEN
BEGIN
TABLE'·[Nl. PAGENO := L;
TABLE"£Nl.LINENO := I;
IF ! POSI'WRITE' ,YI > 0 I OR
I POSI'READ' 1 YI > 0 l THEN
BEGIN
TLCOPYIY,Nl;
WRITELN !CAl I Yl;
END
ELSE
BEGIN
WRITELN !CAl, Yl;
IF POS!'INITTRACE!' 1 ¥1 = 0 THEN
TLCOPY!Y,NI;
END;
N := N + 1;
END
ELSE
BEGIN
WRITELN ICAI 1 Yl;
I'IAINl := FALSE;
END;
I := I + 1;
READLNIZ9X22PRINT,Yl;
WRITELN<ATI23 101 1 Yl;
IF POSI'END. ' 1Yl > 0 THEN
BEGIN
IF INTR02 <> '$$$$' THEN
WRITELNICAI,CONCAT!TAB, 'INTRODUCTION{''' 1 INTR02 1 '''l; 'II;
WRITELNICAI,CONCATITAB, 'ENDTRACE; 'II;
END;
END;
105
FOR K:= I TO 11 DO
w-m
:= •
·;
PUT!Hl;
CLOSEIH,LOCKl;
END;
END;
(t
"AINPART
t)
(1----------------------------------------f)
BEGIN (I GETTABLE t)
TAB := '
';
PAGE <OUTPUll;
QUESTIONI7, 'FRONT' ,INTROll;
QUESTION!13 1 'END' ,INTR02l;
REWRITEITABLE 1CONCATINAHE, ',TABLE'll;
RESET!l9X22PRINT,CONCATINA"E, '.TEXT'll;
REWRITEICAI,CDNCATINAHE, '.CAI.TEXT'll;
y := '
DECLPART;
J := 0;
N := 1;
MINPART;
CLOSEil9X22PRINT,LOCKl;
WRITELNICAI,' 'l;
CLOSEICAI,LOCK>;
TABLEA[Ol.PAGENO := L;
TABLEA[Ol.LINENO := N- 1;
PUT !TABLE);
CLOSEITABLE,LOCKl;
END; (t GETTABLE t)
(1-------------------------------------------------------------------------l)
106
(I
15:6ET6RAPH.TEXT
I)
(t-------------------------------------------------------------------------1)
SEGMENT PROCEDURE 6ET6RAPH;
VAR
VS : CHARSET;
CH : CHAR;
PICTURE : CHAR;
(t----------------------------------------1)
PROCEDURE PROHPTl;
BEGIN
HESSA6E!10,1BO, 'ENTER AVERTEX, CTRL-C FOR NONE
HESSA6E!10,170,'
END;
');
'l;
(1----------------------------------------1)
PROCEDURE PROHPT2 !CH:CHARl;
BEGIN
MESSASE!lO,lBO, 'LOCATE VERTEX 'l;
WCHAR!CHl;
WSTRINS!' BY ARROW KEYS
'l;
MESSAGE!10,170,'
<SPACE> WHEN DONE
END;
'l;
(t----------------------------------------1)
PROCEDURE PROHPT3;
BEGIN
MESSA6E!10 1 1BO, 'ENTER !EDSEl !COSTl<SPACE>
HESSA6E(10,170,'
CTRL-C WHEN DONE
END;
(1----------------------------------------1)
PROCEDURE PROHPT4;
BEGIN
WSTRINS!' = 'l;
END;
(1----------------------------------------1)
PROCEDURE ADJUST!VAR VS : CHARSETl;
VAR
N,CH,ACTION : CHAR;
X,Y : INTEGER;
NUMBER,! : INTEGER;
(1--------------------t)
'l;
'l;
107
PROCEDURE BODY;
BEGIN
PROKPT2 !Nl i
PLOTCHARIX,Y,Nl;
REPEAT
ACTION:= CHARREAD![CHRI114l 1 CHRI82l 1 CHRI21l 1CHRI7bl,CHRIBl,
CHRI117l,CHRI108l,CHRIB5l 1CHRI32l,CHRI11l,
CHRI100l,CHRibBl,CHRI10lll;
PLOTCHARIX,Y,' 'l;
CASE ORDIACTIONl OF
114,82,21: IF X<= 2b0 THEN
X:= X+ 5
ELSE
BELL;
108,7b,B : IF X>= 15 THEN
X:= X- 5
ELSE
BELL;
117,85,11: IF Y<= 155 THEN
y := y + 5
ELSE
BELL;
100 1b8,10: IF Y >=15 THEN
y := y - s
ELSE
BELL;
END;
PLOTCHARIX,Y,Nl;
UNTIL ACTION = '
VUJ.NAKE := N;
V[IJ.X := X+ 2;
V[IJ.Y := Y+ 4;
FOR I := 1 TO NUMBER DO
PLOTCHARIV[IJ.X-2,V[IJ.Y-4,V[lJ.NAKEl;
END; (t BODY tl
(1--------------------f)
BEGIN It ADJUST tl
VS := U;
NUMBER := 0;
PROMPTl;
N := CHARREAD!['A' •• 'Z' ,CHRi3lll;
WHILE IORDINl <> 3l DO
BEGIN
IF N IN VS THEN
BEGIN
I : = SEARCH INl;
X:= V[Il.X- 2;
V := V[ll.Y- 4;
END
ELSE
108
BEGIN
VS := VS + [NJ;
HUMBER := NUMBER + 1;
I := NUIIBER;
X := 30;
y := 150;
END;
BODY;
PROI1PT1;
N:= CHARREAD!['A' •• 'Z' ,CHR!3lll;
END;
V[OJ.X := NUIIBER;
V[OJ.Y :=NUMBER;
V[OJ.NAI'IE := 'V';
FOR I := 1 TO NUMBER DO
GTRACE!2 1V[IJ.NAIIE,' 'l;
END; lt ADJUST t)
(1----------------------------------------f)
PROCEDURE INSTRING!VAR 5: I'IESGl;
VAR
1'1 : 11E5G;
CH : CHAR;
BEGIN
5 ·, - ''.I
CH := CHARREAD![' ·,·o· .. '9'Jl;
WHILE CH <> ' ' DO
BEGIN
WCHAR lCHl;
..n ·=• ' '•
I
CH;
5 := CONCATl5 111l;
CH := CHARREADI['
END;
ll[lJ :=
·,·o· .. '9'Jl;
END;
{f----------------------------------------1)
FUNCTION CONVERT!WORD:I1ESGl:INTE6ER;
VAR
I,J : INTEGER;
BEGIN
I := 0;
FOR J := 1 TO LENGTH!WORD> DO
I := 10 * I+ ORD!WORD[JJl-ORDl'O'l;
CONVERT := I;
END;
{f----------------------------------------1)
PROCEDURE ENTERED6E!V5 : CHARSETl;
VAR
109
CHl, CH2 : CHAR;
I : INTEGER;
11SG : 11ESG;
BEGIN (I ENTEREDGE I)
HOJ.COST := 0;
PROI1PT3;
11ESSAGEIO,O,' 'l;
CHI := CHARREADIVS+£CHRI3lll;
IF ORDICHll <> 3 THEN
WCHARICHll;
WHILE IORDICHll <> 3l DO
BEGIN
CH2 := CHARREADIVS-£CH1ll;
WCHARICH2l;
PROI1PT4;
INSTRING!I1SGl;
I := EINDEXICH1,CH2i + EINDEXICH2,CH1l;
IF I = 0 THEN
BEGIN
E[Ol.COST := E[Ol.COST + 1;
I := HOJ.COST;
END;
Hll.Vl :=CHi;
Hll.V2 := CH2;
E£Il.COST := CONVERTII1SGl;
GTRACEI4 1 CH1,CH2l;
CHI := CHARREADIVS+£CHR13lll;
11ESSA6E I0, 0 I •
•) ;
11ESSA6E!O,o,· 'l;
IF ORD!CHll 0 3 THEN
WCHAR ICH 1l ;
END;
END; (t ENTERED6E tl
11----------------------------------------l)
PROCEDURE SAVEVEIA:CHARl;
VAR
I : INTEGER;
F : STRIN6Ul;
BEGIN
F := , ';
HlJ := A;
RENRITEIFV,CONCAT!'I5:GRAPH' ,F, '.VLIST'll;
FOR I := 0 TO V£0l.X DO
BEGIN
FVA[Jl.NAI1E := V[ll.NAI1E;
FVA[J).X := V£IJ.X;
fVA[J).Y := V[ll.Yj
END;
PUTIFVl;
110
CLOSEIFV,LOCKl;
REWRITEIFE,CONCATI'I5:GRAPH' ,F, '.ELIST'll;
FOR I := 0 TO E£0l.COST DO
BEGIN
FEA[ll.Vl := E[JJ.Vl;
FEA[Jl.V2 := E£Il.V2;
FEA[ll.CDST := E[IJ.COST;
END;
PUTIFEl;
CLOSEIFE,LOCKl;
END; If SAVEVE f)
(f----------------------------------------1)
PROCEDURE NEW;
VAR
C : CHAR;
I : INTEGER;
BEGIN If NEW fl
INITTURTLE;
ADJUSTIVSl;
ENTEREDGEIVSl;
INITTURTLE;
FOR I := 1 TO V[OJ.X DO
BEGIN
PLOTCHARIV£IJ.X-2,V£IJ.Y-4,V[IJ.NAHEl;
GTRACE 12, V£ Il.NAHE,' 'l;
END;
FOR I := 1 TO E[OJ.COST DO
GTRACEI4 1E£Il.Vl,E£IJ.V2l;
10 FOR NO SAVEl 'I;
HESSASEI0 1 1BO, 'SAVE AS ? 1 2 3
C := CHARREADI£'0',, '3'Jl;
IF C > '0' THEN
SAVEVE ICl;
.) ;
HESSASEIO,lBO,'
BSAVEICl;
PICTURE := C;
END; It NEW tl
(f----------------------------------------1)
PROCEDURE TOP;
BEGIN
INITTURTLE;
HESSASEIO,lBO, 'GRAPH EDITOR'!;
HESSA6EI0 1 110,' V VIEW LIBRARY SRAPH'l;
HESSASE!0 1 90 1 ' 6 SET ALIBRARY SRAPH'l;
HESSA6EI0,70 1 ' N EDIT ANEW GRAPH' I;
HESSASEI0 150 1 ' Q QUIT'l;
HESSAGEI0 1 10 1 'ENTER YOUR CHOICE--- 'I;
CH := CHARREADI['Q', 'V' 1 'G' ,'N'Jl;
END;
111
{1----------------------------------------1)
PROCEDURE SETS;
VAR
C : CHAR;
BEGIN
INITTURTLE;
MESSASEI0 1 180, 'SET WHICH?
C := CHARREAD!['l' •• '3'll;
BLOADICl;
SETVE!Cl;
PICTURE := C;
END;
1 OR 2 OR 3'1;
{l----------------------------------------1)
PROCEDURE VIEWS;
VAR
C : CHAR;
BEGIN
INITTURTLE;
"ESSASEI0,180, 'VIEW WHICH?
1 OR 2 OR 3'1;
C := CHARREADI['l · •• '3'll;
BLOAD!Cl;
MESSASEIO,l80, 'PRESS ANY KEY TO RETURN HENU'l;
READ!KEYBOARD,Cl;
END;
(1----------------------------------------1)
BEGIN {I GETSRAPH I)
TOP;
WHILE ICH <> 'Q'l OR !NOT !PICTURE IN ['0',, '3'1)) DO
BEGIN
CASE CH OF
'If: NEW;
'6': SETS;
'V': VIEWS;
'Q': BEGIN
INITTURTLE;
BELL;
MESSAGEI0 1 180, 'WARNING: NO DATA LOAD'!;
END;
END;
TOP;
END;
BLOADIPICTUREl;
END; I* SETSRAPH I)
112
(t
IS:INTRODUC.TEXT
t)
(1---------------------------------------------------------------------------f)
SEGMENT PROCEDURE INTRODUC!TUTO:KESGl;
VAR
T : TEXT;
CH : CHAR;
(1----------------------------------------f)
PROCEDURE ONERUN;
VAR
I : INTEGER;
Y : 11ES6;
BEGIN
I := 1;
NRITE!AT!23,0ll;
NHILE !NOT EOF!Tll AND !I <=51 DO
BEGIN
READLN !T 1 Yl;
NRITELN !Yl;
NRITELN;
I := I + 1;
END;
END;
It
ONERUN tl
(1----------------------------------------f)
PROCEDURE INTERACT;
BEGIN
NRITE!AT!l,Ol, '-------------------------------------');
WRITEl'-----------------------------------------'1;
NRITElAT!O,Ol, 'Introduction: N>ext P>RINT Q)uit'l;
CH := CHARREAD!£'N' ,'Q'll;
IF CH = 'P' THEN
PRHHINS;
END;
(1----------------------------------------f)
BEGIN (I INTRODUC tl
PAGE toUT PUT l ;
RESET!T 1CONCAT!TUTO, '.TEXT'll;
DNERUN;
IF NOT EOF!Tl THEN
ONERUN;
CH := ' ';
NHILE !NOT EOF!Tll AND lCH <> 'Q'l DO
BEGIN
9 .
113
INTERACT;
IF CH = 'N' THEN
ONERUN;
END;
IF IEOF!Tl> AND ICH <>
INTERACT;
CLOSE IT, LOCK l ;
PAGE !OUTPUT> ;
END; (t INTRODUC tl
'Q')
THEN
(t---------------------------------------------------------------------------•l
114
It
15:INITTRACE.TEXT
t)
(1---------------------------------------------------------------------------t)
SESI'IENT PROCEDURE INITTRACEIA : HESS>;
VAR
CH : CHAR;
(1----------------------------------------t)
PROCEDURE SETUPSCREEN;
BEGIN (t SETUPSCREEN t)
PASE <OUTPUll ;
LAST := TABLEA[Ol.PASENO;
PRINTICONCATINAME,' .A'l 1 1l;
TOP := 'A';
BOTTOM : = 'B';
IF LAST >= 'B' THEN
PRINTICONCATINAI'IE, '.B'l 1 2l;
RESETIH,CONCAT<NAI'IE, '. ',PASEIDll;
SETIHl;
END; (t SETUPSCREEN t)
(t----------------------------------------1)
PROCEDURE SELECTBREAKPOINTS;
VAR
CH : CHAR;
I,X,Y : INTEGER;
BEGIN (t SELECTBREAKPOINTS
CH := 'D';
t)
I := 0;
WHILE CH <> 'Q' DO
BEGIN
CASE CH OF
'D' : IF I ( TABLEA[OJ.LINEND THEN
BEGIN
I := I
t
1;
CHECKBOTTOI'I II);
END
ELSE
BELL;
'U' : IF I } 1 THEN
BEGIN
I := I - 1;
CHECKTDP<I>;
END
ELSE
BELL;
'S' : IF POSI' <-------',HA£TABLEA£IJ.LINENDJ) = 0 THEN
115
BESIN
HA£TABLEA[IJ.LINENOJ := CONCATIHA£TABLEA[IJ.LINENOJ,
. (-------');
WRITEIATIY,Xl, '(-------'!;
END
ELSE
BELL;
'F' : IF POSI' <-------· ,HA[TABLEA[ll.LINENOJl >0 THEN
BESIN
DELETE!HA[TABLEA(IJ.LINENOJ,
POS(. (-------· ,W£TABLEA[lJ.LINENOJ) ,9>;
WRITEIAT!Y,X-9!,'
',AT!Y,Xll;
END
ELSE
BELL;
'P' : PRINTING;
END;
CHECKKEIIORY!Il;
X:= LEN6THIHA£TABLEA£IJ.LINENOJJ+l;
y := ITABLEA[IJ.LINENO-ll+llt!ORDITABLEA[IJ.PA6EN0[1))-0RDITOP£1J)J;
SOTOXY <X, Yl;
CH := CHARREADI£'D' 1 'S', 'U', 'F', 'Q', 'P'Jl;
END;
END; It SELECTBREAKPOINTS t)
(t----------------------------------------1)
PROCEDURE RESETTEXT;
VAR
L : STRING£ 1J;
I, J : INTEGER;
BEGIN
(t
RESETTEXT
t)
I := 1;
L := TABLEA[lJ.PAGENO;
WHILE I <= TABLEA[OJ.LINENO DO
BEGIN
RESETIH,CONCATINAKE,'. ',Lll;
GETIH>;
CLOSEIH,LOCKl;
REWRITEIH,CONCATINAKE, ·• ',Lll;
WHILE II <= TABLE'"EOJ.LINENOl AND ITABLEA[IJ.PAGENO = Ll DO
BEGIN
J := PQS(' (-------',HA[TABLEA[IJ.LINENOJl;
IF J > 0 THEN
BEGIN
DELETEIHA£TABLEA£IJ.LINENOJ,J,9);
TABLEA[IJ.LINENO := TABLEA[IJ.LINENO + 100;
END;
I:=I+l;
END;
PUT!Hl;
CLOSEIH,LOCKl;
116
IF I <= TABLEA[OJ.LINENO THEN
l := TABLEA(IJ.PAGENO;
END;
END; It RESETTEXT tl
(i----------------------------------------1)
PROCEDURE SELECTGRAPH;
VAR
CH : CHAR;
BEGIN It SELECTGRAPH t)
PROMPT := 1;
PAGE !OUTPUT> ;
WRITEIATI5,0l, 'TRACE WHICH GRAPH?
2 3 ( 0 FOR NO l'l;
CH := CHARREADI£'0'., '3'll;
IF CH <> '0' THEN
BEGIN
GRAF := TRUE;
BLOADICHl;
GETVEICHl;
PLOT;
NOTEEI 'Original',· ·, · · l;
END;
MESSA6EI0 1 180, 'Comaand: N B T 6 E Q'l;
PASEID := 'A';
HEAD := 0;
TAIL := 0;
CURRENT := 0;
NONSTOP := FALSE;
END; 11 SELECTGRAPH tl
(t----------------------------------------1)
BEGIN (t INITTRACE tl
INITTURTLE;
TEXTMDDE;
PAGE!DUTPUTl;
NRITE!AT!5 1 5l,'HARDWARE ENVIRONMENT: 'l;
WRITE!AT!8,7l 1 'IS APRINTER ON LINE? Y/N 'l;
IF CHARREAD!['Y', 'N'll = 'Y' THEN
BEGIN
ONLINE := TRUE;
CLOSE !OUTPUT> ;
RENRITE!OUTPUT, 'PRINTER:'>;
WRITE !CHR (15ll;
CLOSE !OUTPUT> ;
REWRITE!OUTPUT, 'CDNSOLE:'l;
END;
WRITEIATI11,7l, 'COMPUTER MODEL ?'l;
WRITE!AT!13,7l,' + APPLE II PLUS'!;
117
WRITEIATI15 1 7l 1 ' E APPLE// E'l;
IF CHARREADI['+' 1 'E'll = '+' THEN
COMPUTER := '+';
NAIIE := A;
SELECTSRAPH;
RESETITABLE,CONCATINAIIE, '.TABLE'll;
SET ITABLEl;
CLOSEITABLE,LOCKl;
SETUPSCREEN;
SELECTBREAKPOINTS;
CLOSE IH 1LOCKl;
REWRITEIH,CONCAT!NAIIE, '. ',PASEIDll;
PUTIHl;
CLOSEIH,LOCKl;
PAGE IOUTPUT! ;
PROIIPT:= 2;
WRITEIATI12 1 10l, 'PLEASE WAIT FOR SCREEN SET UP' ,ATIO,Oll;
RESETTEXT;
PAGEID := 'A';
SETUPSCREEN;
INIT := TRUE;
PIITl;
END; It INITTRACE
t)
(i-------------------------------------------------------------------------1)
118
(I
15:6TRACE.TEXT
I)
(f---------------------------------------------------------------------------1)
SEGMENT PROCEDURE GTRACEIFLAG:INTEGER; C1,C2:CHARl;
VAR
I : INTEGER;
(1----------------------------------------f)
PROCEDURE DEPOINTIX,Y:INTEGERl;
BEGIN
PENCOLORINONEl;
MOVETO IX, Yl;
PENCOLORIBLACKl;
MOVEIOJ;
END;
(1----------------------------------------f)
PROCEDURE POINTIX,Y:INTEGERl;
BEGIN
PENCOLORINONEl;
110VETOIX,Vl;
PENCOLORIWHITEl;
!'lOVE (OJ;
END;
(t----------------------------------------1)
PROCEDURE REDUCEIA1,Bl,A2,B2 : INTEGER;
VAR X1,Vl,X2,V2,SS : INTEGER!;
VAR
X,V,A,S,S1,52 : REAL;
I : INTEGER;
BEGIN
REDUCE +)
- A2;
V := Bl - B2;
51 := AB5!Xl i
52 := ABS (V);
s := 51 + 52;
IF Sl < 52 THEN
51 := 52;
52 := S;
A := 5QRIXl + SQRIYl;
FOR I := 1 TO 10 DO
BEGIN
S := 151 + S2l I 2;
IF SQR15l >= ATHEN
52 := s
ELSE
(t
X : = A1
~
'
119
Sl := S;
END;
X2
Y2
Xl
Yl
SS
END;
ROUND!A1-!S-11ltX/Sl;
ROUND!B1-lS-11lfY/Sl;
ROUND!Al-llfX/Sl;
ROUNDIB1-11fY/Sl;
ROUND!Sl;
(f REDUCE f)
:=
:=
:=
:=
:=
(i----------------------------------------1)
PROCEDURE LINE!Xl,Y1,X2,Y2 : INTEGER;
FLAG : INTEGER>;
VAR
Al,B1,A2,B2 : INTEGER;
DIST : INTEGER;
(f--------------------1)
PROCEDURE DLINE!Xl,Yl,X2,Y2,D,DEL : INTEGER!;
VAR
X,Y : INTEGER;
S,STEP : REAL;
BEGIN lt DLINE f)
STEP := 4/D;
s :=
0;
X:= X2 - Xl i
Y: = Y2 - Yl;
IF DEL = 1 THEN
WHILE S <= 1 DO
BEGIN
POINTIROUNDIXl+S+Xl,ROUND!Y1+SfYll;
S := S + STEP;
END
ELSE
WHILE S <= 1 DO
BEGIN
DEPOINT!ROUND!Xl+S+Xl,ROUND!Y1+SfYll;
S := S + STEP;
END;
END; (f DLINE f)
(f--------------------1)
BEGIN (I LINE i)
REDUCE!Xl,Y1,X2 1 Y2,A1,Bl,A2,B2,DISTl;
PENCOLORINONEl;
I'IOVETO!Al ,Bl l;
CASE FLAG OF
1 : BEGIN
PENCOLORIWHITEl;
I'IOVETO!A2 1 B2l;
120
END;
2 : BEGIN
PENCDLORIBLACKl;
110VETDIA2,B2l;
DLINE!Al,Bl,A2 1 B2,DIST 10l;
END;
3 : DLINEIA1,Bl,A2,B2,DIST,ll;
END;
END; It LINE t)
(1----------------------------------------t)
PROCEDURE DDTCIRCLEIX,
V: INTEGER>;
(f
DRAW ADOT CIRCLE NITH RADIUS 10
AND CENTER AT !X,Vl t)
BEGIN
PDINT!X+10,V+3 l;
PDINTIX+7 ,V+7 l;
PDINTIX+3 ,V+10l;
PDINTIX-3 ,V+lOl;
PDINTIX-7 ,V+7 l;
PDINTIX-10,Y+3 l;
POINTIX-lO,Y-3 l;
PDINTIX-7 ,Y-7 l;
PDINTIX-3 ,Y-10>;
PDINTIX+3 ,Y-101;
POINTIX+7 ,Y-7 >;
PDINT!X+lO,Y-3 l;
END;
(t----------------------------------------1)
PROCEDURE CRCLIX,Y,J : INTEGER>;
BEGIN
PENCDLOR!NONE>;
11DVETOIX+lO,Y+3l;
IF J = 0 THEN
PENCOLORIBLACKl
ELSE
PENCDLORINHITEl;
HDVETD!X+7,Y+7l;
110VETD!X+3,Y+10l;
110VETD!X-3 1 Y+10l;
11DVETDIX-7,Y+7l;
HDVETO!X-10,Y+3l;
11DVETOIX-10,Y-3l;
110VETOIX-7,Y-7l;
110VETO!X-3,Y-10l;
HOVETD!X+3 1 V-10l;
110VETOIX+7,V-7l;
HDVETOIX+lO,Y-31;
HDVETOIX+10 1 V+3l;
END;
121
(t----------------------------------------1)
PROCEDURE EDGE5ELECTIC1,C2 : CHAR;
FLAG : INTEGER>;
VAR
I,J : INTEGER;
X,V : INTEGER;
1'1 : I'IESG;
BEGIN It EDGESELECT tl
I := SEARCHICll;
J := 5EARCHIC2l;
IF Cl >= C2 THEN
BEGIN
X:= I;
I := J;
J := X;
END;
LINEIV£IJ.X,V£Il.V,V[JJ.X,V[JJ.V,2l;
IF FLAB = 1 THEN
LINEIV[JJ.X,V[IJ.V,V[JJ.X,V[JJ.V,ll
ELSE
LINEIV[JJ.X,V£IJ.V,V[JJ.X,V[JJ.Y 13l;
X:= IV[l).X t V[Jl.Xl DIV 2;
V := IV[Il.V + V[JJ.Vl DIV 2;
I'IESSAGEIX-2,Y-4 1 ''l;
I := EINDEXIC1 1 C2l;
IF I = 0 THEN
I := EINDEXIC2 1 Cll;
STRIE£Il.COST,I'Il;
NSTRIN6111l;
END; It EDGESELECT tl
(t----------------------------------------1)
BEGIN It STRACE
IF GRAF THEN
BEGIN
t)
CASE FLAG OF
1: BEGIN
If VSELECT tl
SEARCHICll;
CRCLIV[Il.X 1 V£Il.Y,ll;
END;
2: BEGIN
It VRELEASE t)
I := SEARCHICll;
CRCLIV[JJ.X,V£Il.Y,Ol;
DOTCIRCLE!V[Il.X,V[Il.Vl;
END;
3: EDSESELECTIC1,C2 1 1l;
It ESELECT tl
I :=
122
4: ED6ESELECT!Cl,C2,2l;
END;
{I
ERELEASE tl
END;
END;
(I
6TRACE
I}
(1---------------------------------------------------------------------------f)
123
(t
IS:PTRACE.TEXT
tl
(1---------------------------------------------------------------------------l)
SEGMENT PROCEDURE PTRACEII:INTEGER; ST:SHORTl;
VAR
Y: INTEGER;
L : INTEGER;
L1 : INTEGER;
(t----------------------------------------1)
PROCEDURE LINEUPDATEIL:INTEGER;ST:SHORT;Y:INTEGERl;
VAR
J,K : INTEGER;
BEGIN (t LINEUPDATE tl
J := LENGTH!HA(Lll;
K :=POSt'; "1 HA[Lll;
IF J > KTHEN
DELETE!HA[Ll,K+l,J-Kl;
HA£Ll := coNCATIHA£Ll,· ·,sT>;
WRITE lATtY ,Ol ,CLEAR,H'"£Ll l;
END;
(1----------------------------------------f)
PROCEDURE SCOLLINGII:INTEGERl;
BEGIN
IF I > 0 THEN
BEGIN
CHECKI'IEI'IORY II l ;
CHECKTOPIIl;
CHECKBOTiOI'I (I l;
END;
END;
(1----------------------------------------t)
PROCEDURE UPDATESCREENIVAR I:INTEGER;ST:SHORTl;
VAR
Y,L : INTEGER;
BEGIN
IF I > 0 THEN
BEGIN
L := TABLE···riJ.LINENO MOD 100;
Y: = IL -1 l +lltiORD!TABLE'··r Il. PAGE NO£ 1l l-ORD !TOP£ 1l l l;
LINEUPDATEIL,ST,Yl;
END
ELSE
BEGIN
124
I := 0 - I;
IF II HOD 21 = 1 THEN
I := I + 1
ELSE
I : = I - 1;
GTRACE!I,ST£1J 1 ST£2Jl;
I := 0 - I;
END;
END;
(1----------------------------------------t)
PROCEDURE INBUFFER!I:INTEGER;ST:SHORTl;
BEGIN
INC!CURRENT>;
INCIHEADl;
IF HEAD = TAIL THEN
INC nAIU;
BUFFER£CURRENTl.TI :=I;
BUFFER£CURRENTJ.STRI := ST;
END;
(1----------------------------------------1)
PROCEDURE BACKUP;
VAR
FOUND : BOOLEAN;
BEGIN (t BACKUP t)
FOUND := FALSE;
WHILE NOT FOUND DO
BESIN
DEC (CURRENT> ;
IF TAIL <> CURRENT THEN
BEGIN
SCOLLIN6!BUFFER£CURRENTl. Til;
UPDATESCREEN!BUFFER£CURRENTJ.TI,BUFFER£CURRENTl.STRil;
IF BUFFER£CURRENTJ.STDP THEN
FOUND := TRUE;
END
ELSE
BEGIN
BELL;
INC l CURRENT>;
FOUND := TRUE;
END;
END;
END; (I BACKUP I)
(t----------------------------------------1)
PROCEDURE NEXT!VAR ASAIN : BOOLEAN!;
VAR
125
FOUND : BOOLEAN;
BESIN (t NEXT I)
FOUND := FALSE;
WHILE NOT FOUND DO
IF HEAD <> CURRENT THEN
BESIN
INC ICURRENT> ;
SCOLLI NS (BUFFER [CURRENTJ; Tl l ;
UPDATESCREENIBUFFER£CURRENTJ.TI,BUFFER£CURRENTJ.STRil;
IF BUFFER£CURRENTJ.STOP THEN
FOUND := TRUE;
END
ELSE
BESIN
ASAIN := FALSE;
FOUND := TRUE;
END;
END; (I NEXT I)
(1----------------------------------------1)
PROCEDURE CONTROL;
VAR
CH : CHAR;
ASAIN : BOOLEAN;
BESIN lt CONTROL tl
ASAIN := TRUE;
WHILE ASAIN DO
BE SIN
cH := cHARREADt£·a·, 'N', ·s· I 'T' I 'E', ·g·, ·p·J>;
CASE CH OF
'T' : TEXTIIODE;
'6' : SRAFIIODE;
'Q' : BESIN
WHILE CURRENT <> HEAD DO
NEXT IASAINl;
NONSTOP := TRUE;
ASAIN := FALSE;
END;
T : BESIN
WHILE CURRENT <> HEAD DO
NEXT IASAINl;
NONSTOP := TRUE;
ENDINS := TRUE;
ASAIN := FALSE;
END;
'N' : NEXTIASAINl;
'B' : BACKUP;
'P' : PRINTINS;
END;
END;
126
END;
(I
CONTROL
I)
(t----------------------------------------1)
BEGIN (I PTRACE I)
IF ItHT THEN
BEGIN
SCOLLING(J);
Ll := TABLEA[IJ.LINENO "OD 100;
IF LENGTH!H'"[LlJ) = POS!';' ,W'[Llll THEN
BEGIN
INBUFFER (J I " ) i
BUFFER[CURRENTJ.STOP := FALSE;
END;
UPDATESCREEN!I 1 STl;
I NBUFFER (J 1Sll i
IF TABLE'·[IJ.LINENO > 100 THEN
BEGIN
BUFFERICURRENTJ.STOP := TRUE;
IF NOT NONSTOP THEN
CONTROL;
END
ELSE
BUFFERICURRENTJ.STOP := FALSE;
END;
END; It PTRACE t)
{1---------------------------------------------------------------------------l)
127
(t
IS:INTERFACE.TEXT
tl
(1---------------------------------------------------------------------------f)
(f----------------------------------------1)
PROCEDURE CLOSING;
VAR
L : STRINGU J;
I,J,K : INTEGER;
BEGIN
PUT!Hl;
CLOSEIH,LOCKl;
I := 1;
L := TABLEhfll.PA6ENO;
WHILE I <= TABLEhfOJ.LINENO DO
BEGIN
RESETIH,CONCATINAME, '. ',Lll;
GET!Hl;
CLOSE!H,LOCKl;
REWRITEIH,CONCATINAME,'. ',Lll;
WHILE II <= TABLE~·[OJ.LINENOJ AND !TABLEh£IJ.PA6ENO = U DO
BESIN
TABLE"·[ IJ. LINENO := TABLE'·[! J.LINENO IIOD 100;
J :=POSt'; ' 1 HAfTABLEAfil.LINENOll;
K:= LENGTHIH'HABLE'·[!J.LINENOll;
IF IK > Jl AND (J > OJ THEN
HAfTABLEA[IJ.LINENOJ := CDPY!HAfTABLEAfiJ.LINENOl,l,Jl;
I:=I+l;
END;
PUT!Hl;
CLOSEIH 1 LOCKl;
IF I <= TABLEA[(}J.LINENO THEN
L := TABLEA[Jl.PAGENO;
END;
END; (t CLOSING t)
(1----------------------------------------f)
PROCEDURE INBUF;
BEGIN
INCICURRENTI;
INCIHEADl;
IF HEAD = TAIL THEN
INCITAIU;
BUFFERfCURRENTJ. STRI : = ' ';
BUFFERfCURRENTl.STOP := FALSE;
END;
(1----------------------------------------i}
PROCEDURE ITRACEINUMBER:INTEGER; INT:INTE6ER>;
VAR
128
ST : SHORT;
BEGIN
STR (I NT 1STl;
PTRACE!NUHBER,STl;
END;
(1----------------------------------------1}
PROCEDURE CTRACEINUHBER:INTEGER; CH:CHARl;
VAR
ST : SHORT;
BEGIN
ST := ' ';
SHlJ := CH;
PTRACEINUHBER,STl;
END;
(1----------------------------------------1)
PROCEDURE RTRACE!NUHBER:INTEGER;X:REALl;
VAR
ST1,5T2 : SHORT;
BEGIN
STRITRUNC!Xl,STll;
STRITRUNCI!X-TRUNC!Xll1100l,ST2l;
STl := CONCATISTl, ', ' 1 ST2l;
PTRACEINUHBER,STll;
END;
(1----------------------------------------1)
PROCEDURE TRACE!NUHBER:INTEGERJ;
BEGIN
PTRACE!NUHBER, ''l;
END;
(1----------------------------------------1)
PROCEDURE VSELECT!Vl:CHAR>;
BEGIN
GTRACE l1, Vl, ' 'l ;
PLOT;
NOTEEI'After selecting vertex · ,Vl 1 • 'I;
INBUF;
BUFFERECURRENTl.TI := -1;
BUFFER£CURRENTl.STRI£1J := Vl;
END;
(1----------------------------------------1)
PROCEDURE VRELEASE!Vl:CHARl;
BESIN
6TRACEI2 1V1,' 'l;
129
PLOT;
NOTEEI'After releasing vertex ',Vl,' 'l;
INBUF;
BUFFERfCURRENTJ.TI := -2;
BUFFERfCURRENTJ.STRI£11 := Vl;
END;
(f----------------------------------------1)
PROCEDURE ESELECTIVl,V2:CHARl;
BEGIN
6TRACEI3,Vl,V2l;
PLOT;
NOTEEI'After selecting edge ',Vl,V2l;
INBUF;
BUFFER£CURRENTJ.TI := -3;
BUFFER£CURRENTJ.STRI£1J := Vl;
BUFFERfCURRENTJ.STRif2J := V2;
END;
(1----------------------------------------1)
PROCEDURE ERELEASEIV1 1 V2:CHAR>;
BEGIN
6TRACEI4 1 Vl,V2J;
PLOT;
NDTEEI'After releasing edge ',Vl,V2l;
INBUF;
BUFFER£CURRENTJ.STRI£1J := Vl;
BUFFER£CURRENTJ.STRI£2J := V2;
END;
(1----------------------------------------f)
PROCEDURE ENDTRACE;
VAR
J : INTEGER;
BESIN
IF ENDINS THEN
BEGIN
ENDING := FALSE;
NONSTOP := FALSE;
J := TABLEAfOJ.LINEND;
TABLEA[JJ.LINENO := ITABLEA[JJ.LINENO MOD 100) + 100;
PTRACE IJ I") j
END;
PASE !OUTPUT>;
NRITEIATI5 15l, 'Thank you for using this package, 'J;
WRITEIATI7 15l,' please wait for resetting data. 'J;
CLOSING;
PASEIOUTPUTJ;
NRITEIATI7,7J, 'THANK Y0 U'J;
END;