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oorrja
GitHub Repository: oorrja/learntosolveit
 Path: blob/master/languages/python/algorithm_binary_representation.py
1240 views
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"""

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Program to do binary representation of various interesting ints.

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"""

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def convert_to_binary(n):

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    binary = []

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    while n:

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        binary.append(str(n % 2))

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        n /= 2

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    binary.reverse()

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    return "".join(binary)

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for i in range(20, 30):

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    print((i, convert_to_binary(i)))

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hexa_values = ['0', '1', 'A', 'FF', 'DEADBEEF', 'CAFEBABE']

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for each in hexa_values:

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    dec = int(each, 16)

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    print((each, convert_to_binary(dec)))

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"""

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Find out if the machine is storing it in the one's complement or two's

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complement.

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1 is stored as 0000 0001

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-1 in 1's complement is 1111 1110

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-1 in 2's complement is 1111 1111

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"""

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import struct

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if ord(struct.pack('b', -1)[0]) == 255:

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    print('twos complement')

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else:

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    print('ones complement')

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for i in range(200, 255):

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    print((hex(i)))

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for i in range(0, 256):

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    print((chr(i), i, hex(i)))

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"""

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Binary Addition and Subtraction

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"""

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a = 20

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b = 10

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a_bin = convert_to_binary(a)

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b_bin = convert_to_binary(b)

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if len(a_bin) > len(b_bin):

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    b_bin = b_bin.rjust(len(a_bin), '0')

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elif len(a_bin) < len(b_bin):

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    a_bin = a_bin.rjust(len(b_bin), '0')

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def sum_bin(a, b):

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    rules = {('0', '0'): (0, 0),

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             ('0', '1'): (1, 0),

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             ('1', '0'): (1, 0),

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             ('1', '1'): (0, 1)

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             }

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    carry = 0

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    sum = 0

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    result = ""

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    for x, y in zip(reversed(a), reversed(b)):

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        sum = rules[(x, y)][0]

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        if carry:

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            sum = rules[(str(sum), str(carry))][0]

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        result += str(sum)

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        carry = rules[(x, y)][1]

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    if carry:

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        result += str(1)

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    return result[::-1]

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def sub_bin(a, b):

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    ones_complement = ""

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    for c in b:

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        if c == '0':

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            ones_complement += '1'

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        elif c == '1':

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            ones_complement += '0'

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    b = ones_complement

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    b = sum_bin(b, '1'.rjust(len(b), '0'))

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    rules = {('0', '0'): (0, 0),

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             ('0', '1'): (1, 0),

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             ('1', '0'): (1, 0),

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             ('1', '1'): (0, 1)

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             }

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    carry = 0

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    sum = 0

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    result = ""

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    for x, y in zip(reversed(a), reversed(b)):

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        sum = rules[(x, y)][0]

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        if carry:

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            sum = rules[(str(sum), str(carry))][0]

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        result += str(sum)

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        carry = rules[(x, y)][1]

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    # unlike addition carry should be discarded.

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    return result[::-1]

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print(('a', a, a_bin))

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print(('b', b, b_bin))

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print(('a+b ', sum_bin(a_bin, b_bin)))

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print(('a-b ', sub_bin(a_bin, b_bin)))

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