30 lines
1.1 KiB
Python
30 lines
1.1 KiB
Python
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def pylong_join(count, digits_ptr='digits', join_type='unsigned long'):
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"""
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Generate an unrolled shift-then-or loop over the first 'count' digits.
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Assumes that they fit into 'join_type'.
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(((d[2] << n) | d[1]) << n) | d[0]
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"""
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return ('(' * (count * 2) + ' | '.join(
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"(%s)%s[%d])%s)" % (join_type, digits_ptr, _i, " << PyLong_SHIFT" if _i else '')
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for _i in range(count-1, -1, -1)))
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# although it could potentially make use of data independence,
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# this implementation is a bit slower than the simpler one above
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def _pylong_join(count, digits_ptr='digits', join_type='unsigned long'):
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"""
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Generate an or-ed series of shifts for the first 'count' digits.
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Assumes that they fit into 'join_type'.
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(d[2] << 2*n) | (d[1] << 1*n) | d[0]
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"""
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def shift(n):
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# avoid compiler warnings for overly large shifts that will be discarded anyway
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return " << (%d * PyLong_SHIFT < 8 * sizeof(%s) ? %d * PyLong_SHIFT : 0)" % (n, join_type, n) if n else ''
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return '(%s)' % ' | '.join(
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"(((%s)%s[%d])%s)" % (join_type, digits_ptr, i, shift(i))
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for i in range(count-1, -1, -1))
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