Pipeline Execution of Instruction Types

4.2.13 MPYDP Instruction

The MPYDP instruction uses the E1 through E10 phases of the pipeline to complete its operations (see Table 4−15). The lower 32 bits of src1 are read on E1 and E2, and the upper 32 bits of src1 are read on E3 and E4. The lower 32 bits of src2 are read on E1 and E3, and the upper 32 bits of src2 are read on E2 and E4. The lower 32 bits of the result are written on E9, and the upper 32 bits of the result are written on E10. The MPYDP instruction is executed on the .M unit. The functional unit latency for the MPYDP instruction is 4. The status is written to the FMCR on E9. Figure 4−25 shows the fetch, decode, and execute phases of the pipeline that the MPYDP instruction uses.

Table 4−15. MPYDP Instruction Execution

Pipeline

E1

E2

E3

E4

E5

E6

E7

E8

E9

E10

Stage

 

 

 

 

 

 

 

 

 

 

Read

src1_l

src1_l src1_h

src1_h

 

 

 

 

 

 

 

src2_l src2_h

src2_l

src2_h

 

 

 

 

 

 

Written

 

 

 

 

 

 

 

 

dst_l

dst_h

Unit in use

.M

.M

.M

.M

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 4−25. MPYDP Instruction Phases

PG PS PW PR DP DC E1 E2

E3 E4

E5

E6 E7 E8 E9 E10

9 delay slots

SPRU733

Pipeline

4-31

Page 363
Image 363
Texas Instruments TMS320C67X/C67X+ DSP manual 15. Mpydp Instruction Execution