Functional Unit Hazards
6-47
TMS320C67x Pipeline
6.3.11 4-Cycle Instructions
Four-cycle instructions use the E1 through E4 phases of the pipeline to com-
plete their operations (see Table 6–26). The following instructions are 4-cycle
instructions:
-
ADDSP
-
DPINT
-
DPSP
-
DPTRUNC
-
INTSP
-
MPYSP
-
SPINT
-
SPTRUNC
-
SUBSP
The sources are read on E1 and the results are written on E4. The 4-cycle in-
structions are executed on the .M or .L units. The status is written to the FMCR
or FADCR on E4. Figure 6–19 shows the pipeline phases the 4-cycle instruc-
tions use.
Table 6–26. 4-Cycle Execution
Pipeline
Stage
E1
E2
E3
E4
Read
src1
src2
Written
dst
Unit in use
.L or .M
Figure 6–19. 4-Cycle Instruction Phases
PG
PS
PW
PR
DP
DC
E1
E2
E3
E4
3 delay slots
6.3.12 INTDP Instruction
The INTDP instruction uses the E1 through E5 phases of the pipeline to com-
plete its operations (see Table 6–27).
src2 is read on E1, the lower 32 bits of
the result are written on E4, and the upper 32 bits of the result are written on
E5. The INTDP instruction is executed on the .L units. The status is written to
the FADCR on E4. Figure 6–20 shows the pipeline phases the INTDP instruc-
tions use.