On Tue, Oct 16, 2018 at 9:51 AM Jerry James <[email protected]> wrote:
> Sadly, no.
Here is the challenge, Python aficionados. The attached file,
test.pyx, can be processed like this on Fedora 28 with Cython 0.28.4:
"cythonize -3 test.pyx". That succeeds and generates code that Does
The Right Thing.
On Rawhide with Cython 0.29rc2, that fails as noted earlier in this
thread. The name PyLongObject cannot be imported with cimport. How
does the code need to change to compute the same result?
Thanks,
--
Jerry James
http://www.jamezone.org/
from cpython.object cimport Py_SIZE
from cpython.longintrepr cimport PyLongObject, PyLong_SHIFT, digit
cdef enum:
ERR_TYPE = 1
ERR_INDEX = 2
ERR_OVERFLOW = 3
cdef inline long dig(const digit* D, int n):
return (<long>D[n]) << (n * PyLong_SHIFT)
cdef bint do_stuff_to_a_long(x, long* value, int* err) except -1:
cdef const digit* D = (<PyLongObject*>x).ob_digit
cdef Py_ssize_t size = Py_SIZE(x)
cdef int BITS_IN_LONG = 8 * sizeof(long) - 1
cdef long lead
cdef long lead_3_overflow = (<long>1) << (BITS_IN_LONG - 2 * PyLong_SHIFT)
if size == 0:
value[0] = 0
err[0] = 0
elif size == 1:
value[0] = dig(D, 0)
err[0] = 0
elif size == -1:
value[0] = -dig(D, 0)
err[0] = 0
elif size == 2:
value[0] = dig(D, 0) + dig(D, 1)
err[0] = 0
elif size == -2:
value[0] = -(dig(D, 0) + dig(D, 1))
err[0] = 0
elif size == 3:
lead = D[2]
if lead < lead_3_overflow:
value[0] = dig(D, 0) + dig(D, 1) + dig(D, 2)
err[0] = 0
else:
err[0] = ERR_OVERFLOW
elif size == -3:
lead = D[2]
if lead < lead_3_overflow:
value[0] = -(dig(D, 0) + dig(D, 1) + dig(D, 2))
err[0] = 0
elif D[0] == 0 and D[1] == 0 and lead == lead_3_overflow:
# Special case for LONG_MIN
value[0] = (<long>-1) << BITS_IN_LONG
err[0] = 0
else:
err[0] = ERR_OVERFLOW
else:
# 4 digits or more: guaranteed overflow
err[0] = ERR_OVERFLOW
return 1
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