Inverting Condition In Conditional Jump Instructions - Motorola DSP56600 Manual

Example 7-1 First Example—Original Code with Conditional
_else
_endif
Example 7-2 First Example—Code with Conditional Branch
Replaced by Conditional Execution Opcodes (IFcc)
In the second example, the Tcc instruction is used in parallel with a
move instruction to replace a conditional branch, saving 6 cycles.
Example 7-3 Second Example—Original Code with Conditional
_next
Example 7-4 Second Example—Code with Conditional Branch
Replaced by Conditional Execution Opcodes (Tcc)
tgt
7.1.3 Inverting Condition in Conditional Jump
Instructions
The conditional JUMP and BRANCH instructions require
additional cycle when the condition is not true and the target is not
taken. It is advised to choose the exact condition of the JUMP such
that in most cases, the target will be taken.
MOTOROLA Optimizing DSP56300/DSP56600 Applications
Branch
tst a
bgt _else
add x0,b
bra _endif
add y0,b
tst a
add x0,b
add y0,b
Branch
ble _next
move y0,b
move r1,r2
y0,b r1,r2
ifgt
ifle
Compact Opcode Use
Cycle Count of an Instruction
7-3