public DowncastingMemoryBlockAccess(MemoryBlock <T> array)
{
_array = array;
if (!PointerHelpers.IsPrimitiveIntegerType(typeof(T)))
{
throw new ArgumentException("DowncastingMemoryBlockAccess can only cast to primitive integer types");
}
_elemSize = PointerHelpers.GetElementSize(typeof(T));
}
public UpcastingMemoryBlockAccess(MemoryBlock <byte> array, int absoluteByteOffset = 0)
{
_array = array;
_byteOffset = absoluteByteOffset;
if (!PointerHelpers.IsPrimitiveIntegerType(typeof(T)))
{
throw new ArgumentException("UpcastingMemoryBlockAccess can only cast to primitive integer types");
}
_elemSize = PointerHelpers.GetElementSize(typeof(T));
}
public Pointer <E> ReinterpretCast <E>() where E : struct
{
Type currentType = typeof(T);
Type targetType = typeof(E);
if (!PointerHelpers.IsPrimitiveIntegerType(currentType))
{
throw new InvalidOperationException("Cannot cast a pointer from a non-primitive type");
}
if (!PointerHelpers.IsPrimitiveIntegerType(targetType))
{
throw new InvalidOperationException("Cannot cast a pointer to a non-primitive type");
}
if (currentType == targetType)
{
return((Pointer <E>)(object) this);
}
if (!(this._memory is BasicMemoryBlockAccess <T>))
{
throw new InvalidOperationException("Cannot cast a pointer that has already been cast from another type");
}
// Upcasting - accessing a byte array as a sequence of wide integers
if (currentType == typeof(byte) &&
(targetType == typeof(sbyte) ||
targetType == typeof(short) ||
targetType == typeof(ushort) ||
targetType == typeof(int) ||
targetType == typeof(uint) ||
targetType == typeof(long) ||
targetType == typeof(ulong) ||
targetType == typeof(float) ||
targetType == typeof(double)))
{
MemoryBlock <byte> block = (this._memory as BasicMemoryBlockAccess <byte>).Block;
int targetElemSize = PointerHelpers.GetElementSize(targetType);
return(new Pointer <E>(new UpcastingMemoryBlockAccess <E>(block, _elementsOffset % targetElemSize), _elementsOffset / targetElemSize));
}
// Downcasting - accessing an integer array as a sequence of bytes
if (targetType == typeof(byte) &&
(currentType == typeof(sbyte) ||
currentType == typeof(short) ||
currentType == typeof(ushort) ||
currentType == typeof(int) ||
currentType == typeof(uint) ||
currentType == typeof(long) ||
currentType == typeof(ulong) ||
currentType == typeof(float) ||
currentType == typeof(double)))
{
throw new NotImplementedException("Cannot cast a pointer in this way");
//MemoryBlock<T> block = (this._memory as BasicMemoryBlockAccess<T>).Block;
//int sourceElemSize = PointerHelpers.GetElementSize(currentType);
//return (Pointer<E>)(object)(new Pointer<byte>(new DowncastingMemoryBlockAccess<T>(block), _elementsOffset * sourceElemSize));
}
throw new InvalidOperationException("Cannot cast a pointer from " + currentType.ToString() + " to " + targetType.ToString());
}