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Special case for moving sign bit to fractional part.

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This commit is contained in:
chriseth 2016-05-10 14:07:11 +02:00
parent 02e1c9be0d
commit cf226f0607
1 changed files with 10 additions and 5 deletions
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15
libsolidity/ast/Types.cpp
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@ -767,7 +767,6 @@ shared_ptr<FixedPointType const> RationalNumberType::fixedPointType() const
{
bool negative = (m_value < 0);
unsigned fractionalBits = 0;
unsigned integerBits = 0;
rational value = abs(m_value); // We care about the sign later.
rational maxValue = negative ?
rational(bigint(1) << 255):
@ -788,13 +787,19 @@ shared_ptr<FixedPointType const> RationalNumberType::fixedPointType() const
// modify value to satisfy bit requirements for negative numbers:
// add one bit for sign and decrement because negative numbers can be larger
v = (v - 1) << 1;
if (v > u256(-1))
return shared_ptr<FixedPointType const>();
if (0 == integerPart())
unsigned totalBits = bytesRequired(v) * 8;
solAssert(totalBits <= 256, "");
unsigned integerBits = totalBits >= fractionalBits ? totalBits - fractionalBits : 0;
// Special case: Numbers between -1 and 0 have their sign bit in the fractional part.
if (negative && abs(m_value) < 1 && totalBits > fractionalBits)
{
fractionalBits += 8;
integerBits = 0;
else
integerBits = (bytesRequired(v) * 8) - fractionalBits;
}
if (integerBits > 256 || fractionalBits > 256 || fractionalBits + integerBits > 256)
return shared_ptr<FixedPointType const>();