Multiply Two Single-Precision Floating-Point Values

MPYSP

Pipeline

 

 

 

 

 

 

 

 

Pipeline

E1

E2

E3

E4

 

 

 

 

Stage

 

 

 

 

 

 

 

 

 

 

Read

src1

 

 

 

 

 

 

 

src2

 

 

 

 

 

 

Written

 

 

 

dst

 

 

Unit in use

.M

 

 

 

 

 

 

 

 

If dst is used as the source for the ADDDP, CMPEQDP, CMPLTDP,

 

 

CMPGTDP, MPYDP, or SUBDP instruction, the number of delay slots can be

 

 

reduced by one, because these instructions read the lower word of the DP

 

 

source one cycle before the upper word of the DP source.

 

 

Instruction Type

 

4-cycle

 

 

 

 

 

Delay Slots

3

 

 

 

 

 

Functional Unit

1

 

 

 

 

 

Latency

 

 

 

 

 

 

 

See Also

MPY, MPYDP, MPYSP2DP

 

 

 

 

Example

MPYSP .M1X

A1,B2,A3

 

 

 

 

 

 

Before instruction

 

4 cycles after instruction

A1 C020 0000h

B2 4109 999Ah

A3 xxxx xxxxh

−2.5

A1

C020 0000h

 

 

 

8.6B2 4109 999Ah

A3 C1AC 0000h

−2.5

8.6

−21.5

SPRU733

Instruction Set

3-167

Page 227
Image 227
Texas Instruments TMS320C67X/C67X+ DSP manual Mpysp, MPY, MPYDP, MPYSP2DP