Multifield register having a selection field for selecting a source of an information field

摘要

A data processing system (10) has a multifield register (62) which has two fields, a selection field (90) and an information field (91). The selection field (90) identifies the source of the information loaded in the information field (91). In one embodiment, the multifield register (62) is an interrupt flag register (62) and the selection field (90) identifies which of the two registers portions (59,60) of the interrupt pending register (58) is loaded into the multifield register (62). The low register portion (59) can identify up to thirty-one sources of interrupt requests and the high register portion (60) can identify up to thirty-two sources of interrupt requests even though the information field (91) is only thirty-one bits. This is achievable because the selection field (90) may serves a dual function, namely as a flag bit and as bit-32 of the interrupt pending register (58).