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;
}

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