In this homework, we$$re going to implement control structures using goto statements. Even though goto is not something you should use normally in C programming, we use it here as a tool to get familiar with un$-$structured

programs, which will benefit our upcoming assembly language learning.

$1$ Copy a String

In this task, you will write a C code to implement a function called copy$\_$str$()$ that copies all the characters in the src string to dst string. The prototype of the function is declared as follows:

$1$ void copy$\_$str$($char$*$ src$,$ char$*$ dst$)$;

You can assume dst has enough space to store all the characters from src $.$ Note, you cannot use any type of structured loops, such as for $,$ while $,$ and do$...$while $,$ meaning the only option you can use is goto statement. Of course you can use if$-$else structure when needed; however, no statement is allowed in if or else if or else blocks other than a single goto $.$

Requirements

You must not use structured loops mentioned above;

You must not include any other headers;

You must not use any functions provided in string.h $,$ especially not strcpy$()$ and strlen$().$ Note that your code does not need to calculate string length.

Task $2$ Calculate Dot Product

In this task, you need to write a C function to calculate the dot product between two vectors. The prototype of the function is declared as follows:

$1$ int dot$\_$prod$($char$*$ vec$\_$a$,$ char$*$ vec$\_$b$,$ int length, int size$\_$elem$)$;

where both vec$\_$a and vec$\_$b are integer vectors that contain length number of integers, and the function will return a single integer as the dot product. size$\_$elem is the number of bytes of each element in the vectors.

Note that even though both vectors contain integer values, we do not pass int$*.$ In your implementation, you must not cast the entire vector back to int$*.$ However, casting one element to int$*$ is allowed. As in the previous task, you are not allowed to use loops, so you$$d have to use goto statements.

Similarly, no statement is allowed in if or else if or else blocks other than a single goto $.$

Requirements

You must not use structured loops mentioned above;

You must not cast the entire array into another type; only casting one address to int$*$ at a time is allowed

Task $3$ Sorting Nibbles

In this task, you$$ll write a C function to sort all the nibbles $(4$ bits$)$ in an integer array. The prototype of the function is declared as follows:

$1$ void sort$\_$nib$($int$*$ arr, int length$)$;

where arr is the integer array, while length is the number of integers in that array.

For example, say we have an integer array: int arr$[3]=\{0$x$12$BFDA$09,0$x$9089$CDBA, $0$x$56788910\}.$ One nibble has $4$ bits, so each hexadecimal digit represents a nibble. If we treat them as individual numbers and sort them from smallest to largest and print them out as integers, we have: $0$x$000112560$x$788899990$xAABBCDDF $.$

You can use any sorting algorithm you like, but do not use functions provided by existing libraries such as qsort$().$

Hints

Take a deep breath before you start $!$

The first step you want to do in your code is to separate all the nibbles in that array. Even though each nibble takes only four bits, you can still store one nibble in a char variable. If the array is like this:

int arr$[2]=\{0$x$1234,0$x$4321\}$ you can use bit$-$wise operations and shifting to create an array like this: char nibs$[16]=\{0,0,0,0,1,2,3,4,0,0,0,0,4,3,2,1\}.$ Note how many $0$ are there in nibs : each integer takes four bytes which is eight nibbles, so you need to make sure leading zeros are also considered in the array;

After sorting array nibs $,$ you just need to re$-$group nibbles back into integers, and replace them back to arr $.$ Note the function performs an in$-$place sorting;

$10$ bonus points if you use goto in your code instead of structured loops. $1$

Requirements

You must not use existing libraries to sort;

Write down the sorting algorithm you chose in the comments;

In the comments state if you$$d like to be graded for bonus points. Without the statement no bonus points will be given.

$4$ Starter Code & Tester

You are also provided with a starter code where you can see how to call and test the functions. However, note that passing the demo test in the starter code does not mean your program is entirely correct. You must come up with your own tests, especially edge cases.

$1$Note either you use loops or goto $.$ There$$s no partial bonus points for using mixed goto and loops.

To help you with testing, we also provided a tester file tester$\_$m$1($or tester$\_$x$86,$ depending on your machine type$).$ Put this tester file in the same directory as your C code, and use the following command to generate an executable:

$1$ $ gcc main.c tester$\_$m$1$ assuming the C file you wrote is called main.c $.$ If there$$s no errors reported, you can go ahead and run the tester:

$1$ $ $./$a$.$out $-$h where $-$h is to show you how to use the tester. To test your code, use the following command:

$1$ $ $./$a$.$out $-$t $\{$copystr$|$dotprod$|$sortnibs$|$all$\}$ where the name indicates the task you want to test,or all