DRJ means “Destination register Right-Justification”. In 24-bit mode, it tells the 32-bit register file HW the signification part of the register data that a programmer wants to preserve when loading/storing the register data into a 24-bit word local memory since a byte will be dropped. If the local memory is 32-bit word, then no byte will be dropped. But for compatibility with an application developed with 24-bit word local memory in mind, we load data from the high or low 3 bytes based on the DRJ value.
|