New submission from STINNER Victor <victor.stin...@haypocalc.com>: _PyLong_AsScaledDouble() writes the exponent in a int which have to be multiplied by PyLong_SHIFT to give the power of 2. I proposed to multiply the exponent by PyLong_SHIFT in _PyLong_AsScaledDouble() to directly get the power of 2. It avoids complex code to test integer overflow in code using _PyLong_AsScaledDouble() (the test is only done once, in _PyLong_AsScaledDouble).
I also propose to change exponent type from "int*" to "unsigned int*". Previous maximum exponent was INT_MAX//PyLong_SHIFT (eg. 143165576 for PyLong using base 2^15). The new maximum is now UINT_MAX//PyLong_SHIFT, the double ;-) And since issue #4258 is commited (Use 30-bit digits instead of 15-bit digits for Python integers), PyLong_SHIFT value may be different depending on the compiler option. Using my patch, the long implement will be a little bit more hidden. The function _PyLong_AsScaledDouble() should be private because the name starts with "_". But I see it in Include/longobject.h. In Python, it's used in longobject.c and mathmodule.c. ---------- components: Interpreter Core files: pylong_asscaleddouble-2.patch keywords: patch messages: 84236 nosy: haypo severity: normal status: open title: Don't use PyLong_SHIFT with _PyLong_AsScaledDouble() versions: Python 2.7, Python 3.1 Added file: http://bugs.python.org/file13428/pylong_asscaleddouble-2.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue5576> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
