FT1_N_REG
offset = FT1_N_REG(slice, n, FT1_DA0);
offset = FT1_N_REG(slice, n, FT1_DA1);
offset = FT1_N_REG(slice, n, FT1_DA0_MASK);
offset = FT1_N_REG(slice, n, FT1_DA1_MASK);