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diff --git a/mfbt/decimal/Decimal.cpp b/mfbt/decimal/Decimal.cpp
--- a/mfbt/decimal/Decimal.cpp
+++ b/mfbt/decimal/Decimal.cpp
@@ -618,26 +618,26 @@ Decimal::AlignedOperands Decimal::alignO
Decimal Decimal::ceiling() const
{
if (isSpecial())
return *this;
if (exponent() >= 0)
return *this;
- uint64_t result = m_data.coefficient();
- const int numberOfDigits = countDigits(result);
+ uint64_t coefficient = m_data.coefficient();
+ const int numberOfDigits = countDigits(coefficient);
const int numberOfDropDigits = -exponent();
if (numberOfDigits < numberOfDropDigits)
return isPositive() ? Decimal(1) : zero(Positive);
- result = scaleDown(result, numberOfDropDigits - 1);
- if (sign() == Positive && result % 10 > 0)
- result += 10;
- result /= 10;
+ uint64_t result = scaleDown(coefficient, numberOfDropDigits);
+ uint64_t droppedDigits = coefficient - scaleUp(result, numberOfDropDigits);
+ if (droppedDigits && isPositive())
+ result += 1;
return Decimal(sign(), 0, result);
}
Decimal Decimal::compareTo(const Decimal& rhs) const
{
const Decimal result(*this - rhs);
switch (result.m_data.formatClass()) {
case EncodedData::ClassInfinity:
@@ -660,26 +660,27 @@ Decimal Decimal::compareTo(const Decimal
Decimal Decimal::floor() const
{
if (isSpecial())
return *this;
if (exponent() >= 0)
return *this;
- uint64_t result = m_data.coefficient();
- const int numberOfDigits = countDigits(result);
+ uint64_t coefficient = m_data.coefficient();
+ const int numberOfDigits = countDigits(coefficient);
const int numberOfDropDigits = -exponent();
if (numberOfDigits < numberOfDropDigits)
return isPositive() ? zero(Positive) : Decimal(-1);
- result = scaleDown(result, numberOfDropDigits - 1);
- if (isNegative() && result % 10 > 0)
- result += 10;
- result /= 10;
+ uint64_t result = scaleDown(coefficient, numberOfDropDigits);
+ uint64_t droppedDigits = coefficient - scaleUp(result, numberOfDropDigits);
+ if (droppedDigits && isNegative()) {
+ result += 1;
+ }
return Decimal(sign(), 0, result);
}
Decimal Decimal::fromDouble(double doubleValue)
{
if (std::isfinite(doubleValue))
return fromString(String::numberToStringECMAScript(doubleValue));
@@ -915,16 +916,18 @@ Decimal Decimal::round() const
return *this;
uint64_t result = m_data.coefficient();
const int numberOfDigits = countDigits(result);
const int numberOfDropDigits = -exponent();
if (numberOfDigits < numberOfDropDigits)
return zero(Positive);
+ // We're implementing round-half-away-from-zero, so we only need the one
+ // (the most significant) fractional digit:
result = scaleDown(result, numberOfDropDigits - 1);
if (result % 10 >= 5)
result += 10;
result /= 10;
return Decimal(sign(), 0, result);
}
double Decimal::toDouble() const
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