__asm__ C code in mips-Linux

["Mike K." <linux_linux_2003@hotmail.com>]

extern __inline__ void atomic_add(int i, atomic_t * v)
{
        unsigned long temp;

        __asm__ __volatile__(
                "1:   ll      %0, %1      # atomic_add\n"
                "     addu    %0, %2                  \n"
                "     sc      %0, %1                  \n"
                "     beqz    %0, 1b                  \n"
                : "=&r" (temp), "=m" (v->counter)
                : "Ir" (i), "m" (v->counter));
}


Beginner questions on the above code:
1. what is %0 %1 %2?
2. what is the details meaning of the last two line of the above code?
3. Very thanksful if you can comment each line with detail description  for 
me, thanks a lot!

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