Functional Unit Hazards
6-29
TMS320C67x Pipeline
Table 6–11 shows the instruction hazards for MPYDP instructions executing
on the .M unit.
Table 6–11.
MPYDP .M-Unit Instruction Hazards
Instruction Execution
Cycle
1
2
3
4
5
6
7
8
9
10
11
MPYDP
R
R
R
R
W
W
Instruction Type
Subsequent Same-Unit Instruction Executable
16
16 multiply
Xr
Xr
Xr
n
n
n
Xw
Xw
n
n
4-cycle
Xr
Xr
Xr
Xu
Xw
Xw
n
n
n
n
MPYI
Xr
Xr
Xr
Xu
Xu
Xu
n
n
n
n
MPYID
Xr
Xr
Xr
Xu
Xu
Xu
n
n
n
n
MPYDP
Xr
Xr
Xr
n
n
n
n
n
n
n
Instruction Type
Same Side, Different Unit, Both Using Cross Path Executable
Single-cycle
Xr
Xr
Xr
n
n
n
n
n
n
n
Load
Xr
Xr
Xr
n
n
n
n
n
n
n
Store
Xr
Xr
Xr
n
n
n
n
n
n
n
DP compare
Xr
Xr
Xr
n
n
n
n
n
n
n
2-cycle DP
Xr
Xr
Xr
n
n
n
n
n
n
n
Branch
Xr
Xr
Xr
n
n
n
n
n
n
n
4-cycle
Xr
Xr
Xr
n
n
n
n
n
n
n
INTDP
Xr
Xr
Xr
n
n
n
n
n
n
n
ADDDP/SUBDP
Xr
Xr
Xr
n
n
n
n
n
n
n
Legend:
E1 phase of the single-cyle instruction
R
Sources read for the instruction
W
Destinations written for the instruction
n
Next instruction can enter E1 during cycle
Xr
Next instruction cannot enter E1 during cycle–read/decode hazard
Xw
Next instruction cannot enter E1 during cycle–write hazard
Xu
Next instruction cannot enter E1 during cycle–other resource conflict