Motorola DSP56600 Manual page 89

Compact Opcode Use
Cycle Count of an Instruction
7-4 Optimizing DSP56300/DSP56600 Applications
Example:
frequent_code
rare_error
...
By choosing the inverse of the condition, the code can be optimized
and some cycles can be saved:
rare_error
frequent_code
Another example is the implementation of a CASE structure or an
FSM (Finite State Machine) in code:
switch (a) {
}
The straight forward implementation would be:
_default
_case_0
_case_4
_case_9
_end_case
tst a
blt rare_error
...
tst a
bge frequent_code
...
...
case 0: a +=2; break;
case 4: a = b; break;
case 9: a <<= a; break;
default: a += x0;
tst a
beq _case_0
cmp #4,a
beq _case_4
cmp #9,a
beq _case_9
add x0,a
bra _end_case
add #2,a
bra _end_case
tfr b,a
bra _end_case
asl a
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