Instruction Grouping

Are registers D8-D15 or

Yes

Use a two-word

 

 

R8–R15 used in the

 

 

prefix.

 

 

execution set?

 

 

 

 

 

 

 

No

Continue

Is the set conditionally

Yes

Use a one-word

executed (IFc), or does it

 

 

convey looping

 

 

low-register prefix.

 

 

information?

 

 

 

 

 

 

 

No

Continue

Does the execution set

Yes

No prefix is

contain only one

 

 

 

 

needed.

 

 

instruction?

 

 

 

 

 

 

 

 

 

No

Continue

Does the set contain all

Yes

Can a Type 2 or a Type 3

Type 1 instructions, except for

 

 

 

 

instruction be the last in

a single Type 2 or Type 3

 

 

VLES?

instruction?

No

No

Continue

Use a one-word low-register prefix.

Yes

No prefix is needed.

Figure 5-3. Low Register Prefix Selection Algorithm

SC140 DSP Core Reference Manual

5-11

Page 191
Image 191
Freescale Semiconductor SC140 specifications Low Register Prefix Selection Algorithm