Freescale Semiconductor StarCore SC140 - Manual (Page 191)

Instruction Grouping
SC140 DSP Core Reference Manual 5-11
Figure 5-3. Low Register Prefix Selection Algorithm
Yes
Use a two-word
prefix.
No
Continue
Is the set conditionally
executed (IFc), or does it
convey looping
information?
Yes
Use a one-word
low-register prefix.
No
Continue
Does the execution set
contain only one
instruction? Yes
No prefix is
needed.
No
Continue
Does the set contain all
Type 1 instructions, except for
a single Type 2 or Type 3
instruction? Yes
No
Continue
Are registers D8-D15 or
R8–R15 used in the
execution set?
Use a one-word
low-register prefix. No prefix is
needed.
Can a Type 2 or a Type 3
instruction be the last in
VLES?
Yes
No