浅谈C#各种数组直接的数据复制/转换

void glInterleavedArrays(uint format, int stride, void * pointer);

private static extern void glInterleavedArrays(uint format, int stride, int[] pointer);

public static T2[] Arr2Arr<T1, T2>(T1[] from)
  where T1: struct 
  where T2 :struct
{

  int byteNum = from.Length * from[0].Sizeof();
  T2 testByte = new T2();

  dynamic dFrom = from;
  dynamic dTo = new T2[byteNum / testByte.Sizeof()];

  IntPtr ptr = Marshal.AllocHGlobal(byteNum);
  Marshal.Copy(dFrom, 0, ptr, from.Length);
  Marshal.Copy(ptr, dTo, 0, dTo.Length);
  return dTo;
}

public unsafe static T2[] Arr2Arr<T1, T2>(T1[] from, void * pFrom)
  where T1 : struct
  where T2 : struct
{
  int byteNum = from.Length * from[0].Sizeof();
  T2 testByte = new T2();
  dynamic dTo = new T2[byteNum / testByte.Sizeof()];

  IntPtr ptr = new IntPtr(pFrom);
  Marshal.Copy(ptr, dTo, 0, dTo.Length);
  return dTo;
}

public static T2[] Arr2Arr2<T1, T2>(T1[] from)
  where T1 : struct
  where T2 : struct
{
  var gch = GCHandle.Alloc(from,GCHandleType.Pinned);
  IntPtr ptr = gch.AddrOfPinnedObject();

  int byteNum = from.Length * from[0].Sizeof();
  T2 testByte = new T2();
  dynamic dTo = new T2[byteNum / testByte.Sizeof()];
  Marshal.Copy(ptr, dTo, 0, dTo.Length);
  gch.Free();
  return dTo;
}

public static T2[] Arr2Arr3<T1, T2>(T1[] from)
  where T1 : struct
  where T2 : struct
{
  int byteNum = from.Length * from[0].Sizeof();
  T2 testByte = new T2();
  T2[] dTo = new T2[byteNum / testByte.Sizeof()];

  Array.Copy(from, dTo, dTo.Length);
  return dTo;
}

public static T2[] Arr2Arr4<T1, T2>(T1[] from)
  where T1 : struct
  where T2 : struct
{
  int byteNum = from.Length * from[0].Sizeof();
  T2 testByte = new T2();
  T2[] dTo = new T2[byteNum / testByte.Sizeof()];

  Buffer.BlockCopy(from, 0, dTo, 0, byteNum);

  return dTo;
}

byte[] from = new byte[100];
from[0] = 1;
from[1] = 1;

var last = DateTime.Now;
for (int i = 0; i < 2000000; i++)
{
  。。。
}
Console.WriteLine((DateTime.Now- last).TotalMilliseconds);

//sizeof扩展方法internal static class ExFunc
{
  public static int Sizeof(this ValueType t)
  {
    return Marshal.SizeOf(t);
  }
}