diff options
| -rw-r--r-- | Objects/longobject.c | 62 |
1 files changed, 41 insertions, 21 deletions
diff --git a/Objects/longobject.c b/Objects/longobject.c index 93044ee..54d59c3 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -57,21 +57,34 @@ _PyLong_New(int size) PyObject * PyLong_FromLong(long ival) { - /* Assume a C long fits in at most 5 'digits' */ - /* Works on both 32- and 64-bit machines */ - PyLongObject *v = _PyLong_New(5); + PyLongObject *v; + unsigned long t; /* unsigned so >> doesn't propagate sign bit */ + int ndigits = 0; + int negative = 0; + + if (ival < 0) { + ival = -ival; + negative = 1; + } + + /* Count the number of Python digits. + We used to pick 5 ("big enough for anything"), but that's a + waste of time and space given that 5*15 = 75 bits are rarely + needed. */ + t = (unsigned long)ival; + while (t) { + ++ndigits; + t >>= SHIFT; + } + v = _PyLong_New(ndigits); if (v != NULL) { - unsigned long t = ival; - int i; - if (ival < 0) { - t = -ival; - v->ob_size = -(v->ob_size); - } - for (i = 0; i < 5; i++) { - v->ob_digit[i] = (digit) (t & MASK); + digit *p = v->ob_digit; + v->ob_size = negative ? -ndigits : ndigits; + t = (unsigned long)ival; + while (t) { + *p++ = (digit)(t & MASK); t >>= SHIFT; } - v = long_normalize(v); } return (PyObject *)v; } @@ -81,17 +94,24 @@ PyLong_FromLong(long ival) PyObject * PyLong_FromUnsignedLong(unsigned long ival) { - /* Assume a C long fits in at most 5 'digits' */ - /* Works on both 32- and 64-bit machines */ - PyLongObject *v = _PyLong_New(5); + PyLongObject *v; + unsigned long t; + int ndigits = 0; + + /* Count the number of Python digits. */ + t = (unsigned long)ival; + while (t) { + ++ndigits; + t >>= SHIFT; + } + v = _PyLong_New(ndigits); if (v != NULL) { - unsigned long t = ival; - int i; - for (i = 0; i < 5; i++) { - v->ob_digit[i] = (digit) (t & MASK); - t >>= SHIFT; + digit *p = v->ob_digit; + v->ob_size = ndigits; + while (ival) { + *p++ = (digit)(ival & MASK); + ival >>= SHIFT; } - v = long_normalize(v); } return (PyObject *)v; } |