22 lines
460 B
Python
22 lines
460 B
Python
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__all__ = ["log2_int", "bits_for"]
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def log2_int(n, need_pow2=True):
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if n == 0:
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return 0
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r = (n - 1).bit_length()
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if need_pow2 and (1 << r) != n:
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raise ValueError("{} is not a power of 2".format(n))
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return r
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def bits_for(n, require_sign_bit=False):
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if n > 0:
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r = log2_int(n + 1, False)
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else:
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require_sign_bit = True
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r = log2_int(-n, False)
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if require_sign_bit:
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r += 1
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return r
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