//Функцию из длл описал так:
        [DllImport("genmd5.dll")]
        public static extern unsafe void procMD5hash(int* pTempBuffer, int* pHashBuffer); //<===

//Пытаюсь вызвать:

        byte[] TempBuffer = new byte[255];
        byte[] HashBuffer = new byte[255];

        fixed (int *PTempBuffer = &TempBuffer)
        {
            fixed (int *PHashBuffer = &HashBuffer)
            {
                int* PT=PTempBuffer ;  //<===
                int* PH=PHashBuffer ;  //<===
                procMD5hash(PT, PH);
                lblHash.Text = Convert.ToString(HashBuffer);
            }
        }

  [DllImport("genmd5.dll")]
        public static extern unsafe void procMD5hash(int* pTempBuffer, int* pHashBuffer); //<===

//Пытаюсь вызвать:
         public unsafe void dd()
         {
             byte[] TempBuffer = new byte[255];
             byte[] HashBuffer = new byte[255];

             fixed (byte* PTempBuffer = TempBuffer)
             {
                 fixed (byte* PHashBuffer = HashBuffer)
                 {
                     int* PT =(int*) PTempBuffer;  //<===
                     int* PH = (int*)PHashBuffer;  //<===
                     procMD5hash(PT, PH);
                 }
             }
         }

//mydll.cpp
EXPORT int ZZZZ(int* nn, int* nn2,int a1, int a2,int size)
{
      int Bingo=0;
      int sz=size;
      for (int q = 0; q < sz; q++)
     {
     }
     return Bingo;
}

//usemydll.cs
[DllImport(@"Mydll.dll")]
public static extern int ZZZZ(int* n1,int* n2, int a1, int a2,int size);

int[] NN1 = new int[95000];
int[] NN2 = new int[95000];
unsafe zzzz()
{
 int result;
 fixed (int* N1 = NN1)
            {
                fixed (int* N2 = NN2)
                {
                    int* n1 = N1;
                    int* n2 = N2;
                    result= ZZZZ(n1, n2, 30000, 0, NN1.Length);
                    
                }
            }
}

   public unsafe static int Get_Hash_Code(string s)
        {
            List<char> cc = new List<char>();
            for (int i = 0; i < s.Length; i++) cc.Add(s[i]);
            fixed (char* str = &(cc.ToArray())[0])
            {
                int num3;
                char* chPtr = str;
                int num = 0x1505;
                int num2 = num;
                for (char* chPtr2 = chPtr; (num3 = chPtr2[0]) != '\0'; chPtr2 += 2)
                {
                    num = ((num << 5) + num) ^ num3;
                    num3 = chPtr2[1];
                    if (num3 == 0) break;

                    num2 = ((num2 << 5) + num2) ^ num3;
                }
                int k = (num + (num2 * 0x5d588b65));
                return (num + (num2 * 0x5d588b65));
            }

            return 1;
        }