weird code which compiles

Notice how the do while is sandwiched in the case 0, and others cases lie within this do while loop , this kind of code is called Duff's Device after the guy who wrote this kind of code for the first time . I couldnt believe my eyes , I ran it through the debugger to follow the flow of the code , I adapted the code below from the usenet article where this kind of code was first presented , I just cleaned up the indentation in an attempt to understand what is happening .
http://groups.google.com/groups?selm=2748%40alice.UUCP

Code:

void send( int *to, int *from,int count)
{

	int n=(count+7)/8;
  	switch(count%8)
	{
  			case 0:
		do
		{
			*to = (*from)++;
  			case 7:  *to = (*from)++;
  			case 6:  *to = (*from)++;
  			case 5:  *to = (*from)++;
  			case 4:  *to = (*from)++;
  			case 3:  *to = (*from)++;
  			case 2:  *to = (*from)++;
  			case 1:  *to = (*from)++;
   	  	}while(--n>0);
    }
}

int
main(void)
{
	int a=3,b=4;
	send(&a,&b,3);
	printf("a=%d b=%d",a,b);
	return 0;
}