代写COMP2401、代做ROBOT_RADIUS、代写C/C++编程、代做c/c++代写

日期：2019-03-23 11:15

COMP2401 - Assignment #5

(Due: Mon. Mar 25, 2019 @ 12 noon)

In this assignment, you will make a simulator for simple robots that uses multiple threads and allows

multiple robots to connect to it … with each robot running as its own process.

To begin this assignment, you should download the following files:

simulator.h – contains definitions and structs that will be used throughout your code

simulator.c – contains a template for the code that will run the simulator server

display.c – contains the window/drawing code that you will use to display the robots

stop.c – contains a template for the code for a process that will stop the simulator

robotClient.c – contains a template for the code for a process that will run a single robot

When compiling the files, you will need to include the -lm -lpthread and -lX11 libraries.

(but the -lX11 is only needed for the simulator.c file since it uses a window and graphics.)

Follow the steps below (in order) to complete the assignment:

(1) Examine the simulator.h file. The robots have a radius of ROBOT_RADIUS. Each robot is

represented as an (x,y) location and a direction. The x and y values are the location of the

robot in the window … which will be in the range from ROBOT_RADIUS to (ENV_SIZE -

ROBOT_RADIUS). The direction should always be in the range from -180° to +180°. Each

time a robot moves forward, it moves ROBOT_SPEED pixels in the direction that it is facing.

Each time a robot turns, it turns ±ROBOT_TURN_ANGLE degrees. The Environment

contains up to MAX_ROBOTS robots in an array. numRobots is the number of robots

currently registered with the server. The shutDown flag indicates whether or not the

environment has been shut down, it must be set to 0 upon startup.

(2) The simulator.c file contains the code for the server template. The main function in this file

MUST spawn two threads … one that will repeatedly accept incoming client requests … and

another that will repeatedly redraw the robots in the window. Both of these threads should

continue until the shutDown flag in the Environment has been set at which point the threads

will each exit gracefully. A pointer to the Environment should be passed in when spawning

the threads so that the threads have access to the robots and the shutdown flag.

Write the code so that the two threads call these two functions, respectively:

void *handleIncomingRequests(void *environment)

void *redraw(void *environment)

The redraw() function is in the display.c file and has been completed for you. You MUST

NOT alter any code in the display.c file. When you compile and run the simulator.c file, you

should see a window come up which is empty. Run it in the background (i.e., use &) and then

type ps in the terminal window to see the process id. When you close the window, you should

see some XIO error (don’t worry about this). Then typing ps, you should see that the simulator

is no longer running.

Write the code in the handleIncomingRequests() function so that it starts up the server and

repeatedly waits for incoming user requests. There are three possible incoming requests

defined by the definitions in the simulator.h file: (1) REGISTER, (2) STOP and (3) MOVE_TO.

For now, write code that accepts an incoming request to STOP the simulator. The code

should be based on the TCP version of the client/server sockets that were discussed in the

notes. The incoming command for STOP should come in as a single byte. Upon receiving it,

the server should shut down gracefully and both threads should be stopped cleanly.

Complete the code in the stop.c file so that it attempts to connect to the server and send the

STOP command to the server. Test your code by running the simulator server in the

background and then running the stop program. If all works well, the simulator window should

close and should shut down garecfully. Use ps to make sure that the simulator has indeed

shut down properly as well as the stop program. Make sure that you don’t have any

segmentation faults.

(3) Now add code to the robotClient.c file so that it attempts to register with the running

simulator server. To do this, it should send a REGISTER command byte . It should then

wait for a response from the server that should contain an OK or NOT_OK byte response. If

the response byte was OK, then additional bytes should be received containing the id of the

robot (i.e., its number in the environment array of robots), the randomly chosen (x, y) position

and the randomly chosen direction. Note that it is the simulator server that should choose the

random location and direction (see step (1) above for valid ranges). If you are setting up the

send/receive buffer as unsigned bytes, you will need to split the x, y and direction values into

high and low bytes. You may also want to have an extra byte to indicate the sign of the

direction (i.e., positive or negative) since the magnitude will be 0 to 180. You will need to

adjust the handleIncomingRequests() function in the simulator.c file so that it sends the

appropriate bytes back to the client. When all is working, you should see the robot appear in

the simulator window. You’ll need to run the simulator first and then run the robotClient

process. Once it works, try running a second and third robotClient process … you should

see 2 and then 3 robots appearing. Make sure that the stop process still shuts down the

simulator properly.

(4) There is a limit to how many robots that can be added. It is set as MAX_ROBOTS, which is 20

by default. Adjust the code in the simulator server to deny any registrations that go beyond

this limit. Simply send a NOT_OK response when it is full to capacity. Make sure that the

robotClient handles this response properly. Test everything by adding 20 robots and then try

adding a 21st robot. Make sure that you display an appropriate error message in the

robotClient code so that it is clear when the client is unable to register.

(5) Now add functionality to the robotClient so that it repeatedly moves the robot around in the

environment indefinitely. To move forward, the robot should calculate a new location based

on its current location and direction as follows: (newX, newY) = (x+S*cos(d), y+S*sin(d))

where (x,y) is the current robot location, S is the robot’s speed (in pixels) and d is the robots

direction. The robot should then send the MOVE_TO request to the server simulator which

should contain the following information:

the MOVE_TO command

the robot’s ID

the new location that the robot would like to move to

the robot’s direction

Keep in mind that if you use unsigned char array to send the bytes, you will need to break

down the newX, newY into two bytes (most significant byte and least significant byte). You

will also need to be careful sending the direction (which is ±180°) since an unsigned char only

stores values in the 0-255 range and a signed char in the -128 to +127 range.

The robot should receive a single byte back from the server which has one of 3 values:

1. OK if the robot can move to that location without problems,

2. NOT_OK_BOUNDARY if the robot cannot move to that location because it would go

outside the boundary of the environment, and

3. NOT_OK_COLLIDE if the robot cannot move to that location because it would collide

with another robot.

If all is OK, the robot’s (x,y) location should be updated at the client end. Otherwise, the robot

should turn left or right (chosen randomly) by ROBOT_TURN_ANGLE degrees. To do this, do

not change the (x,y) location, just change the direction. Make sure that the direction always

remains in the ±180° range. Also, set your code up so that when the robot first hits a boundary

or collides with another robot, it computes the random direction to turn towards (CW or CCW).

If the robot is unable to move on any successive turns, it should continue to turn in the SAME

direction again. It should keep turning ROBOT_TURN_ANGLE degrees once per loop

iteration. Only when it is OK to move forward should it begin its forward movement again.

Coding things in this manner will ensure that the robot does not alternate turning back and

forth in what appears to be an indecisive pattern. If coded properly, you should see the robot

turning little by little upon collision.

(6) To make things work, you will need to adjust the handleIncomingRequests() function in the

simulator.c file so that it handles incoming MOVE_TO requests from the robots. It will need

to receive all the incoming data that was sent to it as part of the MOVE_TO request. It will

then need to ensure that the new location request is valid. Write a canMoveTo() function that

determines whether or not the robot can move to that location without collision. It will need to

check the boundary values as well as the locations of all other robots to decide whether to

return a value of OK, NOT_OK_BOUNDARY or NOT_OK_COLLIDE. Test your code with a

single robot to see if it works properly. You can lengthen the usleep() delays to slow things

down and investigate the movements, but you must put them back to their initial values when

things seem to be working properly. Test everything with multiple robots and ensure that the

moving and collisions are working properly. You might end up with robots stuck on each other

… see the next part as a possible explanation,

(7) When registering many robots, each is given an initial start location. Sometimes, the location

of one robot may overlap with the location of another robot and the two can get stuck together.

Adjust the handleIncomingRequests() function in the simulator.c file so that it ensures that

each robot is placed a unique non-overlapping location in the environment. That is, make

sure that the robot can “move to” (i.e., or be initially placed at) the randomly chosen location.

You might want to use a WHILE loop until a good random location is found.

________________________________________________________________________________

IMPORTANT SUBMISSION INSTRUCTIONS:

Submit all of your c source code files as a single tar file containing:

1. A Readme text file containing

your name and studentNumber

a list of source files submitted

any specific instructions for compiling and/or running your code

2. All of your .c source files and all other files needed for testing/running your programs.

3. Any output files required, if there are any.

The code MUST compile and run on the course VM, which is COMP2404B-W19.

If your internet connection at home is down or does not work, we will not accept this as a reason for

handing in an assignment late ... so make sure to submit the assignment WELL BEFORE it is due !

You WILL lose marks on this assignment if any of your files are missing. So, make sure that you hand

in the correct files and version of your assignment. You will also lose marks if your code is not written

neatly with proper indentation and containing a reasonable number of comments. See course

notes for examples of what is proper indentation, writing style and reasonable commenting).