Function init_rom_word 

pub fn init_rom_word(step: &InitStep) -> u64

Pack an init step into the 44-bit ddr2_init_fsm ROM word {cke, cs_n, ras_n, cas_n, we_n, ba[1:0], a[12:0], wait[23:0]} — the SINGLE encoding shared by the emitter and the drift lock, with the command pins taken from ddr2_pins.