Dodatek A

Funkcja piszaca do generatora liczb losowych

 ssize_t read_mem(struct file * file, char * buf, 

size_t count, loff_t *ppos)  

 {  

  unsigned long 	p = *ppos;
  unsigned long 	end_mem;
  ssize_t 	read;

 		  end_mem =__pa(high_memory); 

if (p >= end_mem) 

return 0; 

if (count > end_mem - p) 

count = end_mem - p; 

read = 0; 

#if defined(__sparc__) || defined(__mc68000__) 

/* we don't have page 0 mapped on sparc and m68k.. */ 

if (p < PAGE_SIZE) { 

unsigned long sz = PAGE_SIZE-p; 

if (sz > count)

sz = count; 

if (sz > 0) {  

if(clear_user(buf, sz)) 

return -EFAULT; 

buf += sz; 

p += sz; 

count -= sz;

read += sz; 

 }  

 } 

#endif

if (copy_to_user(buf, __va(p), count))

return -EFAULT;

read += count;

*ppos += read;

return read;

 }