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Issue #23517: Add "half up" rounding mode to the _PyTime API

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This commit is contained in:
Victor Stinner 2015-09-02 01:43:56 +02:00
parent bbdda21a7a
commit 744742320f
4 changed files with 122 additions and 15 deletions
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64
Python/pytime.c
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@ -60,6 +60,17 @@ _PyLong_FromTime_t(time_t t)
#endif
}
static double
_PyTime_RoundHalfUp(double x)
{
if (x >= 0.0)
x = floor(x + 0.5);
else
x = ceil(x - 0.5);
return x;
}
static int
_PyTime_DoubleToDenominator(double d, time_t *sec, long *numerator,
double denominator, _PyTime_round_t round)
@ -75,7 +86,9 @@ _PyTime_DoubleToDenominator(double d, time_t *sec, long *numerator,
}
floatpart *= denominator;
if (round == _PyTime_ROUND_CEILING) {
if (round == _PyTime_ROUND_HALF_UP)
floatpart = _PyTime_RoundHalfUp(floatpart);
else if (round == _PyTime_ROUND_CEILING) {
floatpart = ceil(floatpart);
if (floatpart >= denominator) {
floatpart = 0.0;
@ -124,7 +137,9 @@ _PyTime_ObjectToTime_t(PyObject *obj, time_t *sec, _PyTime_round_t round)
double d, intpart, err;
d = PyFloat_AsDouble(obj);
if (round == _PyTime_ROUND_CEILING)
if (round == _PyTime_ROUND_HALF_UP)
d = _PyTime_RoundHalfUp(d);
else if (round == _PyTime_ROUND_CEILING)
d = ceil(d);
else
d = floor(d);
@ -247,7 +262,9 @@ _PyTime_FromFloatObject(_PyTime_t *t, double value, _PyTime_round_t round,
d = value;
d *= to_nanoseconds;
if (round == _PyTime_ROUND_CEILING)
if (round == _PyTime_ROUND_HALF_UP)
d = _PyTime_RoundHalfUp(d);
else if (round == _PyTime_ROUND_CEILING)
d = ceil(d);
else
d = floor(d);
@ -333,7 +350,19 @@ static _PyTime_t
_PyTime_Divide(_PyTime_t t, _PyTime_t k, _PyTime_round_t round)
{
assert(k > 1);
if (round == _PyTime_ROUND_CEILING) {
if (round == _PyTime_ROUND_HALF_UP) {
_PyTime_t x, r;
x = t / k;
r = t % k;
if (Py_ABS(r) >= k / 2) {
if (t >= 0)
x++;
else
x--;
}
return x;
}
else if (round == _PyTime_ROUND_CEILING) {
if (t >= 0)
return (t + k - 1) / k;
else
@ -359,8 +388,10 @@ static int
_PyTime_AsTimeval_impl(_PyTime_t t, struct timeval *tv, _PyTime_round_t round,
int raise)
{
const long k = US_TO_NS;
_PyTime_t secs, ns;
int res = 0;
int usec;
secs = t / SEC_TO_NS;
ns = t % SEC_TO_NS;
@ -392,20 +423,33 @@ _PyTime_AsTimeval_impl(_PyTime_t t, struct timeval *tv, _PyTime_round_t round,
res = -1;
#endif
if (round == _PyTime_ROUND_CEILING)
tv->tv_usec = (int)((ns + US_TO_NS - 1) / US_TO_NS);
if (round == _PyTime_ROUND_HALF_UP) {
_PyTime_t r;
usec = (int)(ns / k);
r = ns % k;
if (Py_ABS(r) >= k / 2) {
if (ns >= 0)
usec++;
else
usec--;
}
}
else if (round == _PyTime_ROUND_CEILING)
usec = (int)((ns + k - 1) / k);
else
tv->tv_usec = (int)(ns / US_TO_NS);
usec = (int)(ns / k);
if (tv->tv_usec >= SEC_TO_US) {
tv->tv_usec -= SEC_TO_US;
if (usec >= SEC_TO_US) {
usec -= SEC_TO_US;
tv->tv_sec += 1;
}
if (res && raise)
_PyTime_overflow();
assert(0 <= tv->tv_usec && tv->tv_usec <= 999999);
assert(0 <= usec && usec <= 999999);
tv->tv_usec = usec;
return res;
}