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35 lines
803 B
Python
35 lines
803 B
Python
#!/usr/bin/python
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''' Clear a bit in a binary number.
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Like the reverse of set bit:
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1) first create a number filled of 1s,
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with 0 at i (can create 0001000 and ~)
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2) AND the number so it clears the ith bit
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'''
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def clear_bit(num, i):
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mask = ~ (1 << i) # -0b10001
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return bin(num & mask)
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def clear_all_bits_from_i_to_0(num, i):
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mask = ~ ( (1 << (i+1)) - 1)
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return bin(num & mask)
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def clear_all_bits_from_most_sig_to_1(num, i):
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mask = ( 1 << i) -1
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return bin(num & mask)
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if __name__ == '__main__':
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num = int('10010000', 2)
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print clear_bit(num, 4) # '0b10000000'
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num = int('10010011', 2)
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print clear_all_bits_from_i_to_0(num, 2) # '0b10010000'
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num = int('1110011', 2)
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print clear_all_bits_from_most_sig_to_1(num, 2) #'0b11' |