private static UInt16 ShiftArithmetic(ShiftDirectionFunc shiftDirectionFunc, UInt16 ui16Val)
{
// 算術シフトでは、符号ビットの値はそのまま変化しない。
UInt16 signBit = UInt16Utils.GetBit(ui16Val, UInt16Utils.MSB);
UInt16 shiftedValue = ShiftLogical(shiftDirectionFunc, ui16Val);
UInt16 shiftedSignedValue = UInt16Utils.SetBit(shiftedValue, UInt16Utils.MSB, signBit);
return(shiftedSignedValue);
}
private static Word DoShift(
ShiftTypeFunc shiftTypeFunc, ShiftDirectionFunc shiftDirectionFunc, Int32 shiftedOutBitPos,
Word word1, Word word2, out UInt16 lastShiftedOutBit)
{
UInt16 shiftedValue = word1.GetAsUnsigned();
UInt16 shiftCount = word2.GetAsUnsigned();
// BitSize (= 16) 回以上シフトしても、結果は変わらない。
shiftCount = Math.Min((UInt16)UInt16Utils.BitSize, shiftCount);
lastShiftedOutBit = 0;
for (UInt16 shiftIndex = 0; shiftIndex < shiftCount; ++shiftIndex)
{
lastShiftedOutBit = UInt16Utils.GetBit(shiftedValue, shiftedOutBitPos);
shiftedValue = shiftTypeFunc(shiftDirectionFunc, shiftedValue);
}
return(new Word(shiftedValue));
}
private static UInt16 ShiftLogical(ShiftDirectionFunc shiftDirectionFunc, UInt16 ui16Val)
{
UInt16 shiftedValue = shiftDirectionFunc(ui16Val);
return(shiftedValue);
}
