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u128: Add StickyLogicalShiftRight

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MerryMage 2018-07-23 15:57:48 +01:00
parent b0afd53ea7
commit 1fe8f51c54
2 changed files with 43 additions and 0 deletions
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39
src/common/u128.cpp
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@ -92,4 +92,43 @@ u128 operator>>(u128 operand, int amount) {
return {};
}
u128 StickyLogicalShiftRight(u128 operand, int amount) {
if (amount < 0) {
return operand << -amount;
}
if (amount == 0) {
return operand;
}
if (amount < 64) {
u128 result;
result.lower = (operand.lower >> amount) | (operand.upper << (64 - amount));
result.upper = (operand.upper >> amount);
// Sticky bit
if ((operand.lower << (64 - amount)) != 0) {
result.lower |= 1;
}
return result;
}
if (amount < 128) {
u128 result;
result.lower = operand.upper >> (amount - 64);
// Sticky bit
if (operand.lower != 0) {
result.lower |= 1;
}
if ((operand.upper << (128 - amount)) != 0) {
result.lower |= 1;
}
return result;
}
if (operand.lower != 0 || operand.upper != 0) {
return u128(1);
}
return {};
}
} // namespace Dynarmic