Pipeline Execution of Instruction Types

4.2.216 y 16-Bit Multiply Instructions

The 16 16-bit multiply instructions use both the E1 and E2 phases of the pipeline to complete their operations (see Table 4−4). Figure 4−10 shows the fetch, decode, and execute phases of the pipeline that the multiply instructions use.

Figure 4−11 shows the operations occurring in the pipeline for a multiply. In the E1 phase, the operands are read and the multiply begins. In the E2 phase, the multiply finishes, and the result is written to the destination register. Multiply instructions have one delay slot.

Table 4−4. 16 y 16-Bit Multiply Instruction Execution

Pipeline Stage

E1

E2

 

 

 

Read

src1

 

 

src2

 

Written

 

dst

Unit in use

.M

 

 

 

 

Figure 4−10. Multiply Instruction Phases

PG

PS PW

PR

DP

DC

E1

E2 1 delay slot

Figure 4−11.Multiply Instruction Execution Block Diagram

 

 

 

 

 

Functional

 

 

 

 

 

 

 

 

unit

 

 

Operands

 

 

 

 

 

.M

 

 

 

 

 

 

 

 

 

 

 

(data)

 

 

 

 

 

 

Write results

 

 

 

E1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

E2

 

 

 

 

Register file

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SPRU733

Pipeline

4-17

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Texas Instruments TMS320C67X/C67X+ DSP 2 16 y 16-Bit Multiply Instructions, 4 y 16-Bit Multiply Instruction Execution