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ICU-22058 make pointer argument in floorDivide optional

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Check the third argument and not set if it is a nullptr
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Frank Tang 2023-01-18 16:39:17 -08:00 • committed by Frank Yung-Fong Tang
parent da5b047dbe
commit bb0e745e25
1 changed files with 16 additions and 11 deletions
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27
icu4c/source/i18n/gregoimp.cpp
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@ -37,11 +37,13 @@ int32_t ClockMath::floorDivide(double numerator, int32_t denominator,
// For an integer n and representable ⌊x/n⌋, ⌊RN(x/n)⌋=⌊x/n⌋, where RN is
// rounding to nearest.
double quotient = uprv_floor(numerator / denominator);
// For doubles x and n, where n is an integer and ⌊x+n⌋ < 2³¹, the
// expression `(int32_t) (x + n)` evaluated with rounding to nearest
// differs from ⌊x+n⌋ if 0 < ⌈x⌉−x ≪ x+n, as `x + n` is rounded up to
// n+⌈x⌉ = ⌊x+n⌋ + 1. Rewriting it as ⌊x⌋+n makes the addition exact.
*remainder = (int32_t) (uprv_floor(numerator) - (quotient * denominator));
if (remainder != nullptr) {
// For doubles x and n, where n is an integer and ⌊x+n⌋ < 2³¹, the
// expression `(int32_t) (x + n)` evaluated with rounding to nearest
// differs from ⌊x+n⌋ if 0 < ⌈x⌉−x ≪ x+n, as `x + n` is rounded up to
// n+⌈x⌉ = ⌊x+n⌋ + 1. Rewriting it as ⌊x⌋+n makes the addition exact.
*remainder = (int32_t) (uprv_floor(numerator) - (quotient * denominator));
}
return (int32_t) quotient;
}
@ -50,16 +52,16 @@ double ClockMath::floorDivide(double dividend, double divisor,
// Only designed to work for positive divisors
U_ASSERT(divisor > 0);
double quotient = floorDivide(dividend, divisor);
*remainder = dividend - (quotient * divisor);
double r = dividend - (quotient * divisor);
// N.B. For certain large dividends, on certain platforms, there
// is a bug such that the quotient is off by one. If you doubt
// this to be true, set a breakpoint below and run cintltst.
if (*remainder < 0 || *remainder >= divisor) {
if (r < 0 || r >= divisor) {
// E.g. 6.7317038241449352e+022 / 86400000.0 is wrong on my
// machine (too high by one). 4.1792057231752762e+024 /
// 86400000.0 is wrong the other way (too low).
double q = quotient;
quotient += (*remainder < 0) ? -1 : +1;
quotient += (r < 0) ? -1 : +1;
if (q == quotient) {
// For quotients > ~2^53, we won't be able to add or
// subtract one, since the LSB of the mantissa will be >
@ -70,12 +72,15 @@ double ClockMath::floorDivide(double dividend, double divisor,
// values give back an approximate answer rather than
// crashing. For example, UDate values above a ~10^25
// might all have a time of midnight.
*remainder = 0;
r = 0;
} else {
*remainder = dividend - (quotient * divisor);
r = dividend - (quotient * divisor);
}
}
U_ASSERT(0 <= *remainder && *remainder < divisor);
U_ASSERT(0 <= r && r < divisor);
if (remainder != nullptr) {
*remainder = r;
}
return quotient;
}