why anti markovnikov rule is not applied on HCL or HI ?

dear vikrant 
its only possible for Hbr ., 
in the presence of peroxide, the addition of hbr occurs by the free radical mechanism and the orientation becomes anti – markonikov’s . 
this is true only for HBr . 
and in case of Hcl its only rarely observed as far as free radical mechanism is concerned . 
in rare case where free radical mechanism of hcl was noted the orientation was still markonikov’s . 
beacuse the more stable product was formed . 
also , free radical addition of hcl  is energetically unfavourable . 
HOPE IT CLEARS 
REGARDS 

bond strength of HI is too less for it to undergo free radical cleavage initiated by peroxide ion,it’s decomposition to H+ and I- is energetically more favoured whereas in HCl bond is too strong to be cleaved by peroxide free radical, it can only be cleaved by sunlight.

hence bond strength of HBr is just perfect for this mechanism.