Functional Unit Constraints
Pipeline
4-38
SPRU733
Table 4
−
22 shows the instruction constraints for
ADDDP/SUBDP
instructions
executing on the .S unit.
Table 4
−
22. ADDDP/SUBDP .S-Unit Instruction Constraints
Instruction Execution
Cycle
1
2
3
4
5
6
7
ADDDP/SUBDP
R
R
W
W
Instruction Type
Subsequent Same-Unit Instruction Executable
Single-cycle
Xr
Xw
Xw
2-cycle DP
Xr
Xw
Xw
Xw
DP compare
Xr
Xw
Xw
ADDDP/SUBDP
Xr
ADDSP/SUBSP
Xr
Xw
Xw
Branch
Xr
Instruction Type
Same Side, Different Unit, Both Using Cross Path Executable
Single-cycle
Xr
DP compare
Xr
2-cycle DP
Xr
4-cycle
Xr
Load
Store
Branch
Xr
16
×
16 multiply
Xr
MPYI
Xr
MPYID
Xr
MPYDP
Xr
Legend:
= E1 phase of the single-cycle instruction; R = Sources read for the instruction; W = Destinations written for the
instruction;
= Next instruction can enter E1 during cycle; Xr = Next instruction cannot enter E1 during cycle-read/
decode constraint; Xw = Next instruction cannot enter E1 during cycle
−
write constraint