Define “custom” integer-based type?

Question

I have a program that is interfacing with an external library that, among other things, has an unsigned 12-bit value packed in a larger struct.

This used to be 8 bit

Answer 1

Try this (this example shows a custom Int64 type)

public class MyCustomInt64 : CustomValueType
{
    private MyCustomInt64(long value) : base(value) {}        
    public static implicit operator MyCustomInt64(long value) { return new MyCustomInt64(value); }
    public static implicit operator long(MyCustomInt64 custom) { return custom._value; }
}

Implement what you like in the constructor to apply constriants.

Usage

MyCustomInt64 myInt = 27; //use as like any other value type

And here is the reusable base custom value type (add more operators if needed)

public class CustomValueType
{        
    protected readonly TValue _value;

    public CustomValueType(TValue value)
    {
        _value = value;
    }

    public override string ToString()
    {
        return _value.ToString();
    }

    public static bool operator <(CustomValueType a, CustomValueType b)
    {
        return Comparer.Default.Compare(a._value, b._value) < 0;
    }

    public static bool operator >(CustomValueType a, CustomValueType b)
    {
        return !(a < b);
    }

    public static bool operator <=(CustomValueType a, CustomValueType b)
    {
        return (a < b) || (a == b);
    }

    public static bool operator >=(CustomValueType a, CustomValueType b)
    {
        return (a > b) || (a == b);
    }

    public static bool operator ==(CustomValueType a, CustomValueType b)
    {
        return a.Equals((object)b);
    }

    public static bool operator !=(CustomValueType a, CustomValueType b)
    {
        return !(a == b);
    }

    public static TCustom operator +(CustomValueType a, CustomValueType b)
    {
        return (dynamic) a._value + b._value;
    }

    public static TCustom operator -(CustomValueType a, CustomValueType b)
    {
        return ((dynamic) a._value - b._value);
    }

    protected bool Equals(CustomValueType other)
    {            
        return EqualityComparer.Default.Equals(_value, other._value);
    }

    public override bool Equals(object obj)
    {
        if (ReferenceEquals(null, obj)) return false;
        if (ReferenceEquals(this, obj)) return true;
        if (obj.GetType() != this.GetType()) return false;
        return Equals((CustomValueType)obj);
    }

    public override int GetHashCode()
    {
        return EqualityComparer.Default.GetHashCode(_value);
    }
}