/// <summary>
/// Gets array if the slice is over an array, otherwise gets a pointer to memory.
/// </summary>
/// <returns>true if it's a span over an array; otherwise false (if over a pointer)</returns>
/// <remarks>This method can be used for interop, while we are waiting for proper pinning support</remarks>
public unsafe bool TryGetArrayElseGetPointer(out ArraySegment <T> array, out void *pointer)
{
var a = Object as T[];
if (a == null)
{
array = new ArraySegment <T>();
pointer = PtrUtils.ComputeAddress(Object, Offset).ToPointer();
return(false);
}
var offsetToData = SpanHelpers <T> .OffsetToArrayData;
var index = (int)((Offset.ToUInt32() - offsetToData) / PtrUtils.SizeOf <T>());
array = new ArraySegment <T>(a, index, Length);
pointer = null;
return(true);
}
public void Set(ReadOnlySpan <T> values)
{
if (Length < values.Length)
{
throw new ArgumentOutOfRangeException("values");
}
// For native memory, use bulk copy
if (Object == null && values.Object == null)
{
var source = PtrUtils.ComputeAddress(values.Object, values.Offset);
var destination = PtrUtils.ComputeAddress(Object, Offset);
var byteCount = values.Length * PtrUtils.SizeOf <T>();
PtrUtils.Copy(source, destination, byteCount);
return;
}
for (int i = 0; i < values.Length; i++)
{
this[i] = values[i];
}
}
/// <summary>
/// Copies the contents of this span into another. The destination
/// must be at least as big as the source, and may be bigger.
/// </summary>
/// <param name="destination">The span to copy items into.</param>
public bool TryCopyTo(Span <T> destination)
{
if (Length > destination.Length)
{
return(false);
}
// For native memory, use bulk copy
if (Object == null && destination.Object == null)
{
var source = PtrUtils.ComputeAddress(Object, Offset);
var destinationPtr = PtrUtils.ComputeAddress(destination.Object, destination.Offset);
var byteCount = Length * PtrUtils.SizeOf <T>();
PtrUtils.Copy(source, destinationPtr, byteCount);
return(true);
}
for (int i = 0; i < Length; i++)
{
destination[i] = this[i];
}
return(true);
}
/// <summary>
/// platform independent fast memory comparison
/// for x64 it is as fast as memcmp of msvcrt.dll, for x86 it is up to two times faster!!
/// </summary>
internal static bool MemCmp <[Primitive] T>(Span <T> first, Span <T> second)
where T : struct
{
unsafe
{
// prevent GC from moving memory
var firstPinnedHandle = GCHandle.Alloc(first.Object, GCHandleType.Pinned);
var secondPinnedHandle = GCHandle.Alloc(second.Object, GCHandleType.Pinned);
try
{
byte *firstPointer = (byte *)PtrUtils.ComputeAddress(first.Object, first.Offset).ToPointer();
byte *secondPointer = (byte *)PtrUtils.ComputeAddress(second.Object, second.Offset).ToPointer();
int step = sizeof(void *) * 5;
int totalBytesCount = first.Length * PtrUtils.SizeOf <T>();
byte *firstPointerLimit = firstPointer + (totalBytesCount - step);
if (totalBytesCount > step)
{
while (firstPointer < firstPointerLimit)
{ // IMPORTANT: in order to get HUGE benefits of loop unrolling on x86 we use break instead of return
if (*((void **)firstPointer + 0) != *((void **)secondPointer + 0))
{
break;
}
if (*((void **)firstPointer + 1) != *((void **)secondPointer + 1))
{
break;
}
if (*((void **)firstPointer + 2) != *((void **)secondPointer + 2))
{
break;
}
if (*((void **)firstPointer + 3) != *((void **)secondPointer + 3))
{
break;
}
if (*((void **)firstPointer + 4) != *((void **)secondPointer + 4))
{
break;
}
firstPointer += step;
secondPointer += step;
}
if (firstPointer < firstPointerLimit) // the upper loop ended with break;
{
return(false);
}
}
firstPointerLimit += step; // lets check the remaining bytes
while (firstPointer < firstPointerLimit)
{
if (*firstPointer != *secondPointer)
{
break;
}
++firstPointer;
++secondPointer;
}
return(firstPointer == firstPointerLimit);
}
finally
{
if (firstPinnedHandle.IsAllocated)
{
firstPinnedHandle.Free();
}
if (secondPinnedHandle.IsAllocated)
{
secondPinnedHandle.Free();
}
}
}
}
