NEC Network Controller uPD98502 - Manual (Page 501)

APPENDIX A MIPS III INSTRUCTION SET DETAILS
Preliminary User’s Manual S15543EJ1V0UM 501
JR
Jump Register
JR
rs
SPECIAL
0 0 0 0 0 0
0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
31 26 25 21 20 0
6 5 15
JR
0 0 1 0 0 0
6 5
6
Format:
JR rs
Description:
The program unconditionally jumps to the address contained in general register rs, with a delay of one instruction.
When a MIPS16 instruction can be executed, the program unconditionally jumps with a delay of one instruction to
the address indicated by the value of clearing the least significant bit of the general register rs to 0. Then, the
content of the least significant bit of the general register rs is set to the ISA mode bit (internal).
Since 32-bit length instructions must be word-aligned, a JR instruction must specify a target register ( rs) that
contains an address whose two low-order bits are zero when a MIPS16 instruction can be executed. If these low-
order bits are not zero, an address error exception will occur when the jump target instruction is subsequently
fetched.
Operation:
32, 64 T: temp ← GPR [rs]
T+1:
PC ← temp
63..1 || 0
If MIPS16EN = 1 then
else
PC ← temp
endif
ISA MODE
← temp
0
Exceptions:
None