Exam 2021-6-2
DIT635 Development of Embedded and Real-Time Systems
Peiran Wei: 19990922-2490
Question 1 - 9 Points
Circuit Overview:
0~10 degrees :
10~20 degrees :
20~30 degrees:
30~40 degrees:
40-50 degrees:
abnormal temperature:
Source code:
// sources code of Question 1
// date : 6/2/2021
#include // timer headerfile
// sensor pin declaration
const int SENSOR_PIN = A0;
const int SENSOR_VAL_MIN = 20;
const int SENSOR_VAL_MAX = 358;
const int SENSOR_TEMP_MIN = -40;
const int SENSOR_TEMP_MAX = 125;
// LED PINS definitions
const int LED_PIN_MIN = 2;
const int LED_PIN_MAX = 6;
const int LED_COUNT = LED_PIN_MAX - LED_PIN_MIN + 1;
const int lOOP_DELAY = 300;
// definitions of pins` values
int LED_LEVELS[LED_COUNT] = {0,0,0,0,0};
// declaration of temp judge functions
void temp_detect();
// initiate the program
void setup()
{
MsTimer2::set(500, temp_detect); // set the interrupts
MsTimer2::start(); // start the timer and counting
// initiate the led pins
for(int ledPin = LED_PIN_MIN; ledPin <= LED_PIN_MAX; ledPin++) {
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, LOW);
}
}
// change the pins` level
void temp_detect()
{
int sensorVal = analogRead(SENSOR_PIN);
float temp = map(sensorVal, SENSOR_VAL_MIN, SENSOR_VAL_MAX, SENSOR_TEMP_MIN,
SENSOR_TEMP_MAX);
if(temp < 10 && temp >=0) // if the degree is between 0 ~ 10
{
LED_LEVELS[0] = 1;
LED_LEVELS[1] = 0;
LED_LEVELS[2] = 0;
LED_LEVELS[3] = 0;
LED_LEVELS[4] = 0;
}
else if (temp < 20 && temp >=10) // if the degree is between 10 ~ 20
{
LED_LEVELS[0] = 1;
LED_LEVELS[1] = 1;
LED_LEVELS[2] = 0;
LED_LEVELS[3] = 0;
LED_LEVELS[4] = 0;
}
else if (temp < 30 && temp >=20) // if the degree is between 20 ~ 30
{
LED_LEVELS[0] = 1;
LED_LEVELS[1] = 1;
LED_LEVELS[2] = 1;
LED_LEVELS[3] = 0;
LED_LEVELS[4] = 0;
}
else if (temp < 40 && temp >=30) // if the degree is between 30 ~ 40
{
LED_LEVELS[0] = 1;
LED_LEVELS[1] = 1;
LED_LEVELS[2] = 1;
LED_LEVELS[3] = 1;
LED_LEVELS[4] = 0;
}
else if (temp < 50 && temp >=40) // if the degree is between 40 ~ 50
{
LED_LEVELS[0] = 1;
LED_LEVELS[1] = 1;
LED_LEVELS[2] = 1;
LED_LEVELS[3] = 1;
LED_LEVELS[4] = 1;
}
else // otherwise all the leds shut down
{
LED_LEVELS[0] = 0;
LED_LEVELS[1] = 0;
LED_LEVELS[2] = 0;
LED_LEVELS[3] = 0;
LED_LEVELS[4] = 0;
}
}
// the main loop
void loop()
{
for(int i = 0; i < LED_COUNT; i++) {
digitalWrite(LED_PIN_MIN+i, LED_LEVELS[i]);
}
delay(lOOP_DELAY);
}
Question 2 - 7 Points
Source code:
// sources code of Question 2
// date : 6/2/2021
#include // header file declaration
#include
#define Status int // data type declaration
const int MAX = 100; //upper bound
const int MIN = 0; //lower bound
int randnums = 0; // random num generated by server
int randnumc = 0; // random num generated by client
int connected = 0; // whether s and c are connected
int initc = 0;
int inits = 0; //initial flag
// the beginning of server
Status server(int guess)
{
if(!connected) return ; //not connected , failed
if(inits == 0) //generate a random num
{
randnums = rand() % MAX; // 0 ~ 100
inits = 1 ;
}
if(guess!=0)
{
printf("server: received num from client : %d \n", guess);
if(guess < randnums) return -1;
else if(guess > randnums) return 1;
else if(guess == randnums) return 0;
}
}
int client(Status server_flag,int range_l, int range_h) // set up a client
{
if(initc == 0) // start guessing
{
randnumc = rand() % range_h;
initc = 1;
connected = 1; // connected prepared
printf("client: connected the server and the first number is %d \n",randnumc);
return randnumc;
}
else
{
if(server_flag == -1) // too low
{
printf("client: the number is too low, new number is %d \n",randnumc + 1);
randnumc++;// increase the number
return randnumc;
}
else if(server_flag == 1) //too high
{
printf("client: the num if too high, new number is %d\n", randnumc -1);
randnumc--; // decrease the number
return randnumc;
}
else // correct
{
printf("client: correct, the number is %d",randnumc);
return -1; // game over, succeeded
}
}
}
// the beginning of main()
int main()
{
printf("connecting....\n"); // prompt user the actual process
int counter = 0;
int response = -2; // response from the server
int guess = 0; // current number
for(counter=0 ; counter< MAX ; counter ++) // guess process
{
guess = client(response,MIN,MAX); //guess once
if(guess == -1) break; // if succeed, game over
response = server(guess); // else continue, send to server
}
return 0;
}
Question 3 - 7 Points
Source code:
// sources code of Question 3
// date : 6/2/2021
#include // header file declarations
#include
#include
/*Task 1*/
int prime_check(int num) // check the num is prime or not
{
int k , i= 0 ;
k=(int)sqrt(num );
for(i=2;i<=k;i++)
{
if(num%i==0)
break;
}
if(i>k)
{
printf("%d is prime\n",num); // print out results to user
return 1;
}
else
{
printf("%d is not prime\n",num);
return -1;
}
return 0;
}
// the beginning of main()
int main()
{
prime_check(2);
}
Question 4 - 8 Points
Source code:
// sources code of Question 4
// date : 6/2/2021
/* *This program demonstrates the data structure of a binary tree*Your task is specified in the
exam*/
#include // header file declaration
#include
// This is one node of the tree
typedef struct {
int data; // data which is stored in the node
void* left; // pointer to the left sub-tree
void* right; // pointer to the right sub-tree
} Node; /* *This function creates an empty nde*/
/* Task A : print the node */
// print the binary tree type: 0- root , 1- left ,2- eight, level- layer of tree
void printTree(Node *n, int type, int level)
{
int i;
if (NULL == n) // NUll node , failed
return;
printTree((Node *)n->right, 2, level+1);
switch (type) // Recursive printing
// type: 0- root , 1- left ,2- eight, level- layer of tree
{
case 0: //root
printf("%2d\n", n->data);
break;
case 1: // left
for (i = 0; i < level; i++)
printf("\t");
printf("\\\n");
for (i = 0; i < level; i++)
printf("\t");
printf(" %2d\n", n->data);
break;
case 2: //right
for (i = 0; i < level; i++)
printf("\t");
printf(" %2d\n", n->data);
for (i = 0; i < level; i++)
printf("\t");
printf("/\n");
break;
}
printTree((Node *)n->left, 1, level+1);
}
/* Task B : delete the node */
void DeletNode(Node *p, Node *cur, int DelData)
{
Node *subNode = NULL; // sub-nodes
Node *pNode = NULL; // parent nodes
if (cur == NULL)
{
printf("not exist\n");
exit(0);
}
else if (DelData > cur->data)
{
DeletNode((Node *)cur, (Node *)cur->right, DelData);
}
else if (DelData < cur->data)
{
DeletNode((Node *)cur, (Node *)cur->left, DelData);
}
else if(DelData == cur->data)
{
if ((Node *)cur->left == NULL && (Node *)cur->right == NULL)
//the delete nodes are subnodes
{
if (p->left == cur) //left
{
p->left = NULL;
}
else if (p->right == cur) //right
{p->right = NULL;
}
}
}
}
/* Task C : problems */
/*
1.function main didn`t check whether the fromer creation succeeded or not
2.function CreateNode didn`t check whether the current creation succeeded or not
3.the memories are not freed at the end of the program
4.the type of child should not be void*, Node * is better
*/
Node * CreateNode(int val)
{
Node *p; // pointer to the new node
// create the node
p = (Node *) malloc(sizeof(Node)); // store the value
p->data = val; // Left and right child for node
// will be initialized to null
p->left = NULL;
p->right = NULL; // return the new node
return p;
}
/* Task D : delete the tree */
void freeTree(Node *n)
{
if (n == NULL)
return;
// free left
if ((Node *)n->left != NULL)
{
freeTree((Node *)n->left);
n->left = NULL;
}
// free right
if ((Node *)n->right != NULL)
{
freeTree((Node *)n->right);
n->right = NULL;
}
// free root
if (n != NULL)
{
free(n);
n = NULL;
}
}
/* *Main - create a simple tree*/
int main()
{
/*create root*/
Node* root = CreateNode((int)'B'); // create two sub-trees
//Task C: make sure the former creation is correct
if(root == NULL)
{
printf("Failed exit!"); // failed
return -1;
}
printTree(root,0,0);
printf("\n");
root->left = CreateNode('9');
//Task C: make sure the former creation is correct
if(root->left == NULL)
{
printf("Failed exit!"); // failed
return -1;
}
printTree(root,0,0);
root->right = CreateNode(0x20);
//Task C: make sure the former creation is correct
if(root->right == NULL)
{
printf("Failed exit!"); // failed
return -1;
}
printTree(root,0,0); // print the tree
((Node *)root->left)->left = CreateNode(68);
//Task C: make sure the former creation is correct
if(((Node *)root->left)->left== NULL)
{
printf("Failed exit!"); // failed
return -1;
}
printTree(root,0,0);
printf("\n");
((Node *)root->right)->left = CreateNode(1);
//Task C: make sure the former creation is correct
if(((Node *)root->right)->left == NULL)
{
printf("Failed exit!"); // failed
return -1;
}
printTree(root,0,0);
printf("\n");
//Task C - free all memory
freeTree(root);
printTree(root,0,0);
}
Question 5 - 4 Points
1.
For multi-core processors, each core is essentially running on its own. Multithreading does not
mean parallel operations. Programs are executed sequentially in a single core. The system
optimizes resources and automatically schedules threads. All in all, multithreading is not a
prerequisite for fully exploiting CPU performance. For example, in deep learning, the CPU cannot
implement parallel operations, so GPUs are needed.
2.
For a multi-core processor, it is essentially just a collection of multiple single-core sequential
processors. There is no parallel computing unit like GPU on the circuit, so even if multithreading
is used, it only improves efficiency from the level of resource utilization. In short, multi-threading
and multi-core processors do not necessarily improve each other. In order to greatly speed up
the operation of the computer, it is still necessary to consider parallel chips (e.g., GPU, FPGA) or
design special computing units for algorithms.

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