static void * alloc(u_int n, u_int align, int clear){    extern char end[];      int i;    u_long alloced_mem;    if(freemem==0)        freemem=(u_long)end;    freemem = (((u_long)(freemem))+(align)-1)&~((align)-1);    //Step 1 finished.    alloced_mem = freemem;    //Step 2 finished.    freemem +=(((u_long)(n))+(align)-1)&~((align)-1);    //Step 3 finished.    if(clear == 1){        for(i=alloced_mem;i