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Add protection from weirdness while scaling the mantissa to an integer.

This commit is contained in:
Raymond Hettinger 2008-02-01 23:45:44 +00:00
parent 1bcb99a9cb
commit f9859037fc
1 changed files with 10 additions and 5 deletions
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15
Objects/floatobject.c
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@ -1159,6 +1159,7 @@ float_as_integer_ratio(PyObject *v, PyObject *unused)
double self;
double float_part;
int exponent;
int i;
PyObject *prev;
PyObject *py_exponent = NULL;
@ -1198,16 +1199,21 @@ float_as_integer_ratio(PyObject *v, PyObject *unused)
float_part = frexp(self, &exponent); /* self == float_part * 2**exponent exactly */
PyFPE_END_PROTECT(float_part);
while (float_part != floor(float_part)) {
for (i=0; i<300 && float_part != floor(float_part) ; i++) {
float_part *= 2.0;
exponent--;
}
/* Now, self == float_part * 2**exponent exactly and float_part is integral */
if (i == 300) {
/* Could not convert mantissa to an integer */
Py_INCREF(Py_NotImplemented);
return Py_NotImplemented;
}
/* self == float_part * 2**exponent exactly and float_part is integral */
numerator = PyLong_FromDouble(float_part);
if (numerator == NULL) goto error;
/* now self = numerator * 2**exponent exactly; fold in 2**exponent */
/* fold in 2**exponent */
denominator = PyLong_FromLong(1);
py_exponent = PyLong_FromLong(labs((long)exponent));
if (py_exponent == NULL) goto error;
@ -1216,8 +1222,7 @@ float_as_integer_ratio(PyObject *v, PyObject *unused)
if (py_exponent == NULL) goto error;
if (exponent > 0) {
INPLACE_UPDATE(numerator,
long_methods->nb_multiply(numerator,
py_exponent));
long_methods->nb_multiply(numerator, py_exponent));
if (numerator == NULL) goto error;
}
else {