For this assignment you will write a crc integrity checking program will have two modes of operation. your program must implement the crc calculation method involving long division by a polynomial that we discussed in lecture. in "calculation" mode, the program will calculate the crc-12 value for a given input string. in "verification" mode, the program will interpret the last 3 hex characters of an input string as a crc-12 value, and it will then determine whether this is the correct crc-12 value for the input string without those 3 characters. in both modes, the program must report header information, intermediate results, and final results as described further below. the mode and the input string to process will be supplied to your program as command line arguments. the program will be graded according to the grading rubric that appears at the bottom of this assignment.

Of course, some of the recorded functions will very likely invoke others of these functions. It is decent practice to reuse components instead of writing the same block of code in multiple places. Many logical errors can be evaded by doing so, and if any corrections are needed, they can be done conveniently in just one place.

Keep in mind that the basic idea is to break down the overall task into small pieces that can be developed (and tested) separately so you can build your program incrementally.

Program Output

The program must present output consisting of header information, intermediate results, and final results, as described separately below. Sample outputs follow in the next section.

Header Information

The header information should be written on distinct lines as shown in the sample outputs that follow. The individual lines are:

1. The program must first write a string of 62 hyphens (dashes) to serve as a separator, and then, 2 lines below it, the string "CIS3360 Fall 2017 Integrity Checking Using CRC", and then on the next line the string "Author: " followed by your name (or names, if teaming) and a newline.

2. The program must then write the string "The input string (hex): ", followed by the string value of the second command line input argument

3. The program must then write the string "The input string (bin): ", followed by the binary value of the second command line input argument, and then a newline.

4. The program must then write the string "The polynomial that was used (binary bit string): ", followed by the 13-bit binary value of the polynomial given at the top of this assignment with spaces every 4 characters to improve readability.

5. The program must then write the string "Mode of operation: ", followed by either the word "calculation" or "verification", depending on the value of the first command line input argument

6. The content of this line depends on whether the mode is calculate or verify.

a. If in calculation mode, this line should read: "Number of zeroes that will be appended to the binary input: 12"

b. If in verification mode, this line should read: "The CRC observed at the end of the input: ", followed by the binary and hex values for the last 3 hex characters of the input string, as shown in the sample outputs that follow.

Intermediate Results

This section will begin with the string: "The binary string difference after each XOR step of the CRC calculation", followed by a newline.

Following the above statement, this section will show on separate lines the results of each XOR step as described above, with spaces every 4 characters as shown to improve readability.

Note that for calculation mode, you must pad the binary version of the input string with 12 zeroes before you start the division procedure, but for confirmation mode you have two choices. The first step is to remove the last three hex characters demonstrating the observed CRC, in which case you must then pad the rest with 12 zeroes like you were calculating the CRC. The second step is to leave the detected CRC attached to the rest of the input, in which case you should not add zeroes for padding. The difference between these two choices determines how you will interpret the result in the bottom row of the intermediate results output.