Functional Unit Constraints

Table 4−25 shows the instruction constraints for 4-cycle instructions executing on the .M unit.

Table 4−25. 4-Cycle .M-Unit Instruction Constraints

 

 

 

 

Instruction Execution

Cycle

1 2

3

4

5

4-cycle

R

 

W

 

 

 

 

Instruction Type

 

Subsequent Same-Unit Instruction Executable

 

 

 

 

 

 

16 16 multiply

 

n

Xw

n

n

4-cycle

 

n

n

n

n

MPYI

 

n

n

n

n

 

MPYID

 

n

n

n

n

MPYDP

 

n

n

n

n

 

 

 

 

Instruction Type

Same Side, Different Unit, Both Using Cross Path Executable

 

 

 

 

 

 

Single-cycle

 

n

n

n

n

Load

 

n

n

n

n

 

Store

 

n

n

n

n

DP compare

 

n

n

n

n

2-cycle DP

 

n

n

n

n

Branch

 

n

n

n

n

4-cycle

 

n

n

n

n

INTDP

 

n

n

n

n

ADDDP/SUBDP

 

n

n

n

n

 

 

 

 

 

 

Legend: = E1 phase of the single-cycle instruction; R = Sources read for the instruction; W = Destinations written for the instruction; n = Next instruction can enter E1 during cycle; Xw = Next instruction cannot enter E1 during cycle-write constraint

SPRU733

Pipeline

4-41

Page 373
Image 373
Texas Instruments TMS320C67X/C67X+ DSP manual 25 -Cycle .M-Unit Instruction Constraints