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