public static unsafe void UsePointer(this MemoryStream ms, BytePointerWriter f)
{
void ExecAndTrack(byte *p)
=> ms.Position += f(p);
if (ms.TryGetBuffer(out var buf))
fixed(byte *p = &buf.Array[buf.Offset])
ExecAndTrack(p);
fixed(byte *p = &ms.ToArray()[ms.Position])
ExecAndTrack(p);
}
public static unsafe void UsePointer(this UnmanagedMemoryStream ums, BytePointerWriter f)
{
if (ums is MemoryMappedViewStream mmvs)
{
byte *p = null;
var h = mmvs.SafeMemoryMappedViewHandle;
h.AcquirePointer(ref p);
var diff = f(p + ums.Position);
h.ReleasePointer();
ums.Position += diff;
return;
}
ums.Position += f(ums.PositionPointer);
}
