1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64
|
class TestCopy
{
// The unsafe keyword allows pointers to be used within the following method:
static unsafe void Copy(byte[] src, int srcIndex, byte[] dst, int dstIndex, int count)
{
if (src == null || srcIndex < 0 ||
dst == null || dstIndex < 0 || count < 0)
{
throw new System.ArgumentException();
}
int srcLen = src.Length;
int dstLen = dst.Length;
if (srcLen - srcIndex < count || dstLen - dstIndex < count)
{
throw new System.ArgumentException();
}
// The following fixed statement pins the location of the src and dst objects
// in memory so that they will not be moved by garbage collection.
fixed (byte* pSrc = src, pDst = dst)
{
byte* ps = pSrc;
byte* pd = pDst;
// Loop over the count in blocks of 4 bytes, copying an integer (4 bytes) at a time:
for (int i = 0 ; i < count / 4 ; i++)
{
*((int*)pd) = *((int*)ps);
pd += 4;
ps += 4;
}
// Complete the copy by moving any bytes that weren't moved in blocks of 4:
for (int i = 0; i < count % 4 ; i++)
{
*pd = *ps;
pd++;
ps++;
}
}
}
static void Main()
{
byte[] a = new byte[100];
byte[] b = new byte[100];
for (int i = 0; i < 100; ++i)
{
a[i] = (byte)i;
}
Copy(a, 0, b, 0, 100);
System.Console.WriteLine("The first 10 elements are:");
for (int i = 0; i < 10; ++i)
{
System.Console.Write(b[i] + " ");
}
System.Console.WriteLine("\n");
}
} |
Partager