TSK3000A Core Instruction - RFE

Frozen Content

Modified by Admin on Sep 13, 2017

Instruction:

Restore From Exception

Assembler Format:

rfe

Example:

mfc0 t1, COP_ExceptionReturn
j t1
rfe

Description:

Copies the control register bits for previous interrupt mask mode and previous user mode (IEp and UMp) to the current mode bits (IEc and UMc) and copies the old mode bits (IEo and UMo) to the previous mode bits (IEp and UMp). The old mode bits remain unchanged.

Normally an RFE instruction is placed in the delay slot after a JR instruction, in order to restore the PC.

Operation:

IEc <-- IEp
UMc <-- UMp
IEp <-- IEo
UMp <-- UMo

Instruction Type:

R-Type

Encoding:

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0

Latency: 1