FPL Abs bug

[ZhangHuan0407]

FPL16 value = FPL16.MinValue;
FPL16 absValue = value.Abs();
Console.WriteLine($"{value}, {absValue}"); // -140737488355328, -140737488355328
value = new FPL16(-1);
absValue = value.Abs();
Console.WriteLine($"{value}, {absValue}"); // -1, 1

long testValue = long.MinValue;
Console.WriteLine($"{long.MinValue}, {-testValue}"); // -9223372036854775808, -9223372036854775808
try
{
Math.Abs(testValue);
}
catch (Exception ex)
{
// System.OverflowException: Negating the minimum value of a twos complement number is invalid.
Console.WriteLine(ex.ToString());
}

[ZhangHuan0407]

I think the result of FPL16.Abs cannot be negative.
Version: Nuget 30.1.1

// Decompile the code
public FPL16 Abs()
{
return Prescaled((N >= 0) ? N : (-N));
}

// Modified (Haven't tested this code, not 100% sure)
public FPL16 Abs()
{
long newN = N;
if (newN == long.MinValue)
{
newN = long.MaxValue;
}
return Prescaled((newN >= 0) ? newN : (-newN));
}

// dotnet source code
https://referencesource.microsoft.com/#mscorlib/system/random.cs,61
They changed MinValue to MaxValue where they didn't expect an error.

System.Math.Abs throw exception, if value equal long.MinValue.

FixedPoint gets closer to decimal?