Copy speeds (as reported by MSCV++ 6.0 Professional’s Profiler)

Using an array of 16 floats (10,000 copies)

Fastest – a[0] = b[0]; a[1] = b[1] …… etc.

Middle – memcpy(a, b, 64);

Slowest – a[y] = b[y];

Profiler results

Conclusion: don’t use memcpy in matrix/vector classes.

Code used:

int main()
{
	T3();
	T2();
	T1();
	return 0;
}

void T1()
{
	for(int x = 0; x < 5000; x++)
	{
		memcpy(b, a, 64);
		memcpy(a, b, 64);
	}
}

void T2()
{
	for(int x =0; x < 5000; x++)
	{
		b[0] = a[0];
		b[1] = a[1];
		b[2] = a[2];
		b[3] = a[3];
		b[4] = a[4];
		b[5] = a[5];
		b[6] = a[6];
		b[7] = a[7];
		b[8] = a[8];
		b[9] = a[9];
		b[10] = a[10];
		b[11] = a[11];
		b[12] = a[12];
		b[13] = a[13];
		b[14] = a[14];
		b[15] = a[15];

		a[0] = b[0];
		a[1] = b[1];
		a[2] = b[2];
		a[3] = b[3];
		a[4] = b[4];
		a[5] = b[5];
		a[6] = b[6];
		a[7] = b[7];
		a[8] = b[8];
		a[9] = b[9];
		a[10] = b[10];
		a[11] = b[11];
		a[12] = b[12];
		a[13] = b[13];
		a[14] = b[14];
		a[15] = b[15];

	}
}

void T3()
{
	for(int x = 0; x < 5000; x++)
	{
		for(int y = 0; y < 16; y++)
		{
			a[y] = b[y];
		}
		for(y = 0; y < 16; y++)
		{
			b[y] = a[y];
		}
	}
}