Assignment 2

Name: Kshitij Chandrakar
Batch: DS 5
SAP: 500124827

Theoretical selection #

  1. Bit Stuffing: Bit stuffing is a technique used in data transmission to avoid confusion between data and control characters. It involves inserting a non-data bit (usually a 0) after a specific pattern of consecutive bits (e.g., 5 consecutive 1s). This prevents the occurrence of reserved patterns, like flags or control sequences, within the actual data stream.

  2. Bit Stuffing vs Byte Stuffing:

    • Bit Stuffing: Involves inserting a bit (usually 0) after a specific number of consecutive 1s to prevent the flag pattern from appearing in the data.
      • Example: If the flag is 01111110, and the data contains 11111, a 0 is inserted after the fifth 1, changing it to 111110.
    • Byte Stuffing: Involves inserting a special byte (e.g., 0x7E) to represent reserved control characters when they appear in the data stream.
      • Example: If 0x7E is the flag, and the data contains 0x7E, it would be stuffed with another byte, like 0x7D 0x5E.

  3. Bit Stuffing (assuming 011111 is the flag sequence):

    • Original bit stream: 01111110 110111111011111010
    • Stuffed bit stream: 01111110 110111111011111010 → Insert a 0 after five consecutive 1s.
      • Result: 01111110 110111111011111010 becomes 01111110 1101111101111101010

    Destuffing:

    • Take the stuffed stream and remove the 0 after five consecutive 1s.
      • Result: 01111110 110111111011111010 (original).

  4. Advantages and Disadvantages of Bit Stuffing:

    • Advantages:
      • Prevents data sequences from mimicking control sequences like flags.
      • Ensures reliable data transfer without control character conflicts.
    • Disadvantages:
      • Adds overhead by increasing the size of the transmitted data.
      • Increases complexity in both encoding and decoding.

Practical Section #

Code #

Stuffing Function #
def Stuff(inp = "110111111011111010"):
    stuff = ""
    c = 0
    print("Input is:", inp)
    for bit in inp:
        if bit == "1":
            c += 1
        else:
            c = 0
        stuff += bit
        if c == 5:
            stuffed += "0"
            c = 0
    print("Bit Stuffed Output is:", stuff)
    return stuff
Destuffing Function #
def Destuff(inp = ""):
    print("Stuffed Input is", inp)
    destuff = ""
    c = 0
    i = 0
    while i < len(inp):
        destuff += inp[i]
        if inp[i] == "1":
            c += 1
        else:
            c = 0
        if c == 5:
            i += 1
            c = 0
        i += 1
    print("Bit Destuffed Output is:", destuff)
    return destuff
Main #
def main():
    inp = input("Enter Input (Blank for default): ")
    if inp != "":
        print("-------------In-------------")
        out = Stuffing(inp=inp)
        print("-------------Out-------------")
        Destuff(inp=out)
    else:
        print("Using Defaults")
        print("-------------In-------------")
        out = Stuff(inp="011111")
        print("-------------Out-------------")
        Destuff(inp=out)
    pass
if __name__ == '__main__':
    main()

Output #

My Image