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The Language of Robots
The Source Code
Robot programs are written in source code and then translated by the
assembler into robot-understandable object code. Source code is composed
of comments, labels, and instructions.
1. Comments:
Comments are used for documenting the source code. Comments can appear
anywhere in the program as long as they are preceded by a semi-colon.
] A TO B ;This stores a in b
This is an example of a comment on the same line as an instruction.
2. Labels:
A label is a reference point used to identify sections within a program.
Labels are used in instructions to change the order of execution of the
program.
A label is composed of a group of 2 or more alpha-numeric characters
immediately following a RETURN symbol (]). A label must start with an
alpha character (A to Z) and must be less than 32 characters long. A
label can not be the same as any of the register names or command
words.
3. Instructions
Instructions are used to control the robot's micro-computer brain.
Instructions may contain register names, command words and numbers
(-1024 to +1024)
Command words: a) 'TO' stores a value in a register
b) 'IF' compares two values and alters program flow. use these
conditions:
= equal
# not equal
< less than
> greater than
c) 'GOTO' jumps to a label in the prog.
d) 'GOSUB' calls a subroutine
e) 'ENDSUB' returns from a subroutine
f) math operators
+ adds two values
- subtracts two values
* multiplies two values
/ divides two values
Restrictions:
a) no parentheses allowed
b) use only integer numbers between +1024 and -1024
c) you must use a condition sign when using an 'IF'
d) you may store negative NUMBERS in a register, but you can't store
negative REGISTERS in a register.
e) all math operations are done from left to right
The TO command
The TO command is used to store a value in a register.
] 240 TO A
This example line of source code causes the computer to load the
accumulator with a value of 240 and the store it in the A register.
] B TO A
This example causes the computer to load the accumulator with the
contents of the B register and then store it in the A register.
] 0 TO SPEEDX TO SPEEDY
This example causes the computer to load the accumulator with 0 and
store it first in the SPEEDX and register and then in the SPEEDY
register. This could be used to stop a robot's movement.
NOTE: Negative numbers can be stored as in the following example:
] -240 TO SPEEDX
But, you CANNOT store the negative of a register in that manner. For
example:
] -B TO A
Will NOT store the negative of B in A. To store a negative of a register
subtract the register from zero. For example:
] 0 -B TO A
Arithmetic commands (+ - * /)
Arithmetic operations can be performed on a value stored in the
accumulator. Whenever the program encounters one of the arithmetic signs
it performs the calculation using the contents of the accumulator and
the value that follows. It then stores the results of the calculation in
the accumulator.
] 240 + 100 TO A
This example loads 240 into the accumulator, adds 100 to it, and stores
the result (340) in the A register.
The IF command
The IF command is used to compare a value with the contents of a
register. It can test to see if a register is less than (<), greater
than (>), equal to (=), or not equal to (#) a value. If the comparison
is true the computer executes the next TO, GOTO, GOSUB or ENDSUB
command. If the comparison is false the computer skips the next TO,
GOTO, GOSUB or ENDSUB commands.
The GOTO command
A GOTO command causes the program to change it's sequence of execution
by going to a designated label and continuing its execution from there.
A GOTO instruction must always be followed by a label.
The GOSUB command
Another way to change the execution sequence is to use a GOSUB command.
A GOSUB instruction is similar to a GOTO command. GOSUB must always be
followed by a label. GOSUB will cause the program to go to the
designated label and continue the execution until it reaches an ENDSUB.
When it encounters the ENDSUB, the program will then return to the next
instruction after the GOSUB.
Caution:
Some illegal statements will be translated by the assembler, but then
will do odd things when executed.
Programming a Robot
In order to make a robot perform, you must construct a program using the
RobotWar language and your own strategy. This chapter gives examples of
how instructions can be constructed, suing registers. numbers, and
commands, and how those instructions can be labeled and sequenced to
create program routines.
Movement
Moving about the battlefield is an action a robot performs. To start a
robot moving, store a value in the speedx or speedy register.
] 20 to speedx
] 250 to speedy
would start the robot moving down and to the right. However, the robot
would continue to move in those directions, and would eventually hit a
wall. Therefore, you must stop it at some point, by storing a zero in
the speedx and speedy registers.
] 0 to speedx
A robot can only accelerate or brake at 40 decimeters/second. Even
though 120 is entered into speedx register, it takes 3 seconds of
acceleration to obtain that speed. Conversely, if your robot is
travelling at 120 decimeters/sec it takes 3 seconds to stop the robot,
after storing 0 in the speedx register.
A movement routine can be established, by incorporating the starting and
stopping procedures into a test loop.
] 256 TO SPEEDX
]MOVER1
] IF X > 230 GOTO STOP
]STOP
] 0 TO SPEEDX
Moves the robot to the right until it's X position is tested to be
greater than 230 and then it stops.
Monitoring Damage
Monitoring damage is vital to a robot's survival. When a robot detects a
hit, it usually moves to avoid being repeatedly hit by the enemy. By
using the DAMAGE register, a damage detection routine can be
established. This routine is usually nested inside another routine's
loop so that the robot can be checking for damage while it is performing
some other action.
] DAMAGE TO D
Saves current damage in register D.
]DAM1
] IF DAMAGE # D GOTO MOVE
When any damage is incurred, the DAMAGE register will change, but
register D will not. Therefor, any difference between the two registers
will indicate that the robot has been hit. In this example any
difference will cause the program to go to the label MOVE.
Scanning
Another important action a robot performs is scanning. When a robot
scans it is using it's radar beams to detect the location of other
robots and walls. To emit a radar beam, store a number, between 0 and
359 in the RADAR register.
] 90 TO RADAR
Will send a radar beam in the 90-degree direction, and when the beam
returns, it's value will be stored in the RADAR register. A routine to
determine if the robot has spotted another robot is:
]LOOK
] AIM + 5 TO AIM
] AIM TO RADAR
] IF RADAR < 0 GOTO SHOOT
] GOTO LOOK
When the program executes this routine, it first encounters the label
LOOK and goes on to the next instruction. This instruction (AIM + 5 TO
AIM) increments the angle in which the gun is aimed, five degrees. The
next instruction (AIM TO RADAR) aligns the angle of the radar to the
angle of the gun, emits a radar beam in that direction, and then stores
the results of that beam in the RADAR register.
The next instruction (IF RADAR < O GOTO SHOOT) analyzes the results of
the radar's findings. If the RADAR register contains a positive number,
there are no robots in that direction and the comparison will be false.
Since the comparison is false, the next command will be ignored and the
program will go on to the next command (GOTO LOOK). This command will
cause the program to go to the label LOOK. This completes the loop and
the scan routine will continue until a robot is found.
If the RADAR register contains a negative number, After the beam
returns, the comparison (IF RADAR < 0) will be true. Therefor, the next
command (GOTO SHOOT) will be executed. In this case the program sequence
would branch to the instruction following the label SHOOT.
Shooting
It is usual procedure to execute a shooting routine when an enemy is
spotted.
]SHOOT
] 0 - RADAR TO SHOT
] GOTO LOOK
Is an example of a simple shoot routine. Since a robot has been spotted
by radar, a negative number is presently stored in the RADAR register.
The enemy robot is that number (ignoring the negative sign) of meters
away. In order to obtain a positive number of the distance, the program
subtracts RADAR from 0. This new positive number is then stored in the
SHOT register. Storing the number in the SHOT register causes the gun to
fire a shell that has been set to explode at that distance, in the
direction indicated by the contents of the AIM register.
Random Number Generation
The RANDOM register is used to generate random numbers. A few examples
of random number routines are:
] 100 TO RANDOM
] RANDOM TO A
This routine stores 100 in the RANDOM register, which sets the limit for
the generator. The generator then returns a random number from 0 to 99
and stores it in the RANDOM register. That value is then stored in A by
the TO command. From then on each time the contents of the RANDOM
register is stored in a register, the generator will return a different
number. The limit of the generator will only change when a new value is
stored in the RANDOM register by using the TO command.
] B + 1 - A TO RANDOM
] RANDOM + A TO C
This routine stores a random number between A and B into the C
register.
A Sample robot in source code
;SAMPLE ROBOT 'RANDOM'
] 250 TO RANDOM ;INITIALIZE RANDOM -- 250
MAXIMUM
]
]START
] DAMAGE TO D ;SAVE CURRENT DAMAGE
]
]SCAN
] IF DAMAGE # D GOTO MOVE ;TEST -- MOVE IF HURT
] AIM+17 TO AIM ;CHANGE AIM IF OK
]
]SPOT
] AIM TO RADAR ;LINE RADAR WITH LAUNCHER
] IF RADAR>0 GOTO SCAN ;CONTINUE SCAN IF NO ROBOT
] 0-RADAR TO SHOT ;CONVERT RADAR READING TO
]DISTANCE AND FIRE
] GOTO SPOT ;CHECK IF ROBOT STILL THERE
]
]MOVE
] RANDOM TO H
] RANDOM TO V ;PICK RANDOM PLACE TO GO
]
]MOVEX
] H-X*100 TO SPEEDX ;TRAVEL TO NEW X POSITION
] IF H-X>10 GOTO MOVEX ;TEST X POSITION
] IF H-X<-10 GOTO MOVEX ;TEST X POSITION
] 0 TO SPEEDX ;STOP HORIZONTAL MOVEMENT
]
]MOVEY
] V-Y*100 TO SPEEDY ;TRAVEL TO NEW Y POSITION
] IF V-Y>10 GOTO MOVEY ;TEST Y POSITION
] IF V-Y<-10 GOTO MOVEY ;TEST Y POSITION
] 0 TO SPEEDY ;STOP VERTICAL MOVEMENT
] GOTO START ;START SCANNING AGAIN
]
Writing and Editing Source Code
Robot programs are entered into the computer using a text editor.
The text editor may be entered by selecting option 3 from the Main Menu,
or by selecting option 6 from the Assembler menu.
Text-Editor Procedure
When you first enter the text editor, you will see a blank screen with
some numbers at the bottom and a flashing square at the top. The numbers
at the bottom show the length of the text, and the file name under which
it is stored. The flashing square is called the cursor, and is the
computer equivalent of a pen for writing characters. As you use the
text-editor you will be operating in two modes; the add mode and the
cursor mode. The add mode is used to delete text at the cursor, move the
cursor around in the text, adjust the position of the text on the
screen, load source code files from the catalog, and save source code
files to the catalog.
The blank screen indicates that the current text-editor file is empty.
At this point there are two available options. One option is to begin
writing a new source code, and the other option is to edit a robot that
has already been stored.
Ctrl-A to enter the add mode. The letter "A" will appear in the lower
RIGHT corner of the screen. You can now create a new source code file.
Esc Esc exits you from the add mode.
Ctrl-S to save the file on the disk. The word "SAVE" will appear on the
left side of the screen. To save the new robot program you just created
you must give it a name. The name can be no longer than 7 characters and
must not be the same as any other robot on the disk.
Ctrl-L loads a file from the disk. The word "LOAD" will appear on the
left side of the screen.
Cursor Mode
You are now ready to perform the second available option when the
text-editor has been loaded, which is editing the source code file. When
editing source code you will use the cursor mode to delete text at the
cursor, move the cursor around in the text, adjust the position of the
text on the screen, load source code files, and save source code files.
These functions are described below:
1. Cursor Movement
The cursor can be moved to any location in the file by using the five
keys on the right side of the keyboard.
A) The RETURN key moves the cursor up one line
B) The left and right arrow keys.
C) The slash (/) key moves the cursor down one line.
To move the cursor all the way in any direction on the screen, press the
Esc key and then the direction key.
Once you have positioned the cursor where you want it, there are several
options. Either exit to the add mode, and write some text or stay in the
cursor mode and use a cursor function.
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