con_4bit_shift
con |= 0xf << con_4bit_shift(offset);
con &= ~(0xf << con_4bit_shift(offset));
con &= ~(0xf << con_4bit_shift(offset));
con |= 0x1 << con_4bit_shift(offset);
con &= ~(0xf << con_4bit_shift(offset));
con &= ~(0xf << con_4bit_shift(con_offset));
con |= 0x1 << con_4bit_shift(con_offset);