/// <summary>
/// Reads a signed integer with the specified range from an IValueReader.
/// </summary>
/// <param name="reader">IValueReader to read the value from.</param>
/// <param name="name">Name of the value to read.</param>
/// <param name="minValue">Minimum (inclusive) value that the read value can be.</param>
/// <param name="maxValue">Maximum (inclusive) value that the read value can be.</param>
/// <returns>Value read from the IValueReader.</returns>
/// <exception cref="ArgumentOutOfRangeException"><c>maxValue</c> is out of range.</exception>
public static int ReadUInt(this IValueReader reader, string name, int minValue, int maxValue)
{
if (maxValue < minValue)
{
throw new ArgumentOutOfRangeException("maxValue", "MaxValue must be greater than or equal to MinValue.");
}
// Find the number of bits required for the range of desired values
var maxWriteValue = (uint)(maxValue - minValue);
var bitsRequired = BitOps.RequiredBits(maxWriteValue);
// Read the value, which is the offset from the minimum possible value, then add it to the minimum
// possible value
var offsetFromMin = reader.ReadUInt(name, bitsRequired);
return(minValue + (int)offsetFromMin);
}
/// <summary>
/// Initializes the <see cref="EnumHelper{T}"/> class.
/// </summary>
/// <exception cref="MethodAccessException"><typeparamref name="T"/> is not an enum.</exception>
static EnumHelper()
{
var supportedCastTypes = new Type[] { typeof(byte), typeof(sbyte), typeof(short), typeof(ushort), typeof(int) };
// Make sure we have an enum
if (!typeof(T).IsEnum)
{
throw CreateGenericTypeIsNotEnumException();
}
// Get the defined enum values
_values = Enum.GetValues(typeof(T)).Cast <T>().ToCompact();
// Check if we have an underlying enum type that supports our ToInt/FromInt operations
var underlyingType = Enum.GetUnderlyingType(typeof(T));
if (supportedCastTypes.Contains(underlyingType))
{
// Create the funcs to cast to/from an int
_toInt = CreateToInt();
_fromInt = CreateFromInt();
// Get all the defined values casted to int
var valuesAsInt = _values.Select(_toInt);
// Find the min and max values
_minValue = valuesAsInt.Min();
_maxValue = valuesAsInt.Max();
Debug.Assert(_minValue <= _maxValue);
// Find the difference between the min and max so we can cache how many bits are required for the range
var diff = _maxValue - _minValue;
Debug.Assert(diff >= 0);
Debug.Assert(diff >= uint.MinValue);
var bitsReq = BitOps.RequiredBits((uint)diff);
Debug.Assert(bitsReq > 0);
Debug.Assert(bitsReq < byte.MaxValue);
_bitsRequired = (byte)bitsReq;
}
}
/// <summary>
/// Writes a signed integer with the specified range to an IValueWriter.
/// </summary>
/// <param name="writer">IValueWriter to write to.</param>
/// <param name="value">Value to write.</param>
/// <param name="name">Name of the value to write.</param>
/// <param name="minValue">Minimum (inclusive) value that the written value can be.</param>
/// <param name="maxValue">Maximum (inclusive) value that the written value can be.</param>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="value"/> is greater than <paramref name="maxValue"/>
/// or less than <paramref name="minValue"/>.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="maxValue"/> is less than <paramref name="minValue"/>.</exception>
public static void Write(this IValueWriter writer, string name, int value, int minValue, int maxValue)
{
if (value < minValue || value > maxValue)
{
throw new ArgumentOutOfRangeException("value", "Value parameter must be between minValue and maxValue.");
}
if (maxValue < minValue)
{
throw new ArgumentOutOfRangeException("maxValue", "MaxValue must be greater than or equal to MinValue.");
}
// Find the number of bits required for the range of desired values
var maxWriteValue = (uint)(maxValue - minValue);
var bitsRequired = BitOps.RequiredBits(maxWriteValue);
// Subtract the minimum value from the value since we want to write how high above the minimum value
// the value is, not the actual value
var offsetFromMin = (uint)(value - minValue);
writer.Write(name, offsetFromMin, bitsRequired);
Debug.Assert((value - minValue) <= maxWriteValue);
Debug.Assert((1 << bitsRequired) >= maxWriteValue);
}
