Bltzal, Branch on less than zero and link – NEC Network Controller uPD98502 User Manual
Page 459
APPENDIX A MIPS III INSTRUCTION SET DETAILS
Preliminary User’s Manual S15543EJ1V0UM
459
BLTZAL
Branch On Less Than Zero And Link
BLTZAL
rs
REGIMM
0 0 0 0 0 1
BLTZAL
1 0 0 0 0
offset
31
26 25
21 20
16 15
0
6
5
5
16
Format:
BLTZAL rs, offset
Description:
A branch target address is computed from the sum of the address of the instruction in the delay slot and the 16-bit
offset, shifted left two bits and sign-extended. Unconditionally, the address of the instruction after the delay slot is
placed in the link register,
r31. If the contents of general register rs are smaller than zero when compared to zero,
then the program branches to the target address, with a delay of one instruction.
General register
r31 should not be specified as general register rs. If register r31 is specified, restarting may be
impossible due to the destruction of
rs contents caused by storing a link address. Even such instructions are
executed, an exception does not result.
Operation:
32
T:
target
← (offset
15
)
14
|| offset || 0
2
condition
← (GPR [rs]
31
= 1)
GPR [31]
← PC + 8
T+1: if condition then
PC
← PC + target
endif
64
T:
target
← (offset
15
)
46
|| offset || 0
2
condition
← (GPR [rs]
63
= 1)
GPR [31]
← PC + 8
T+1: if condition then
PC
← PC + target
endif
Exceptions:
None