2.2.4 ISR_ALIAS

ISR_ALIAS(vector, target_vector)

Aliases a given vector to another one in the same manner as the ISR_ALIASOF attribute for the ISR() macro. Unlike the ISR_ALIASOF attribute macro however, this is compatible for all versions of GCC rather than just GCC version 4.2 onwards.

Note:

This macro creates a trampoline function for the aliased macro. This will result in a two cycle penalty for the aliased vector compared to the ISR the vector is aliased to, due to the JMP/RJMP opcode used.

Example: 
    ISR(INT0_vect)
    {
        PORTB = 42;
    }

    ISR_ALIAS(INT1_vect, INT0_vect);