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B-38 PPC405 Core User’s Manual
B.8 Branch Instructions
The architecture provides conditional and unconditional branches to any storage location. The
conditional branch instructions test condition codes set previously and branch accordingly.
Conditional branch instructions may decrement and test the Count Register (CTR) as part of
determination of the branch condition and may save the return address in the Link Register (LR). The
target address for a branch may be a displacement from the current instruction address (CIA), or may
be contained in the LR or CTR, or may be an absolute address.
Table B-9. Branch Instructions
Mnemonic Operands Function
Other Registers
Changed Page
b target Branch unconditional relative.
LI
← (target – CIA)
6:29
NIA ← CIA + EXTS(LI ||
2
0)
9-19
ba Branch unconditional absolute.
LI
← target
6:29
NIA ← EXTS(LI ||
2
0)
bl Branch unconditional relative.
LI
← (target – CIA)
6:29
NIA ← CIA + EXTS(LI ||
2
0)
(LR)
← CIA + 4.
bla Branch unconditional absolute.
LI
← target
6:29
NIA ← EXTS(LI ||
2
0)
(LR)
← CIA + 4.
bc BO, BI, target Branch conditional relative.
BD
← (target – CIA)
16:29
NIA ← CIA + EXTS(BD ||
2
0)
CTR if BO
2
= 0. 9-20
bca Branch conditional absolute.
BD
← target
16:29
NIA ← EXTS(BD ||
2
0)
CTR if BO
2
= 0.
bcl Branch conditional relative.
BD
← (target – CIA)
16:29
NIA ← CIA + EXTS(BD ||
2
0)
CTR if BO
2
= 0.
(LR)
← CIA + 4.
bcla Branch conditional absolute.
BD
← target
16:29
NIA ← EXTS(BD ||
2
0)
CTR if BO
2
= 0.
(LR)
← CIA + 4.
bcctr BO, BI Branch conditional to address in CTR.
Using (CTR) at exit from instruction,
NIA
← CTR
0:29
||
2
0.
CTR if BO
2
= 0. 9-26
bcctrl CTR if BO
2
= 0.
(LR)
← CIA + 4.
bclr BO, BI Branch conditional to address in LR.
Using (LR) at entry to instruction,
NIA
← LR
0:29
||
2
0.
CTR if BO
2
= 0. 9-30
bclrl CTR if BO
2
= 0.
(LR)
← CIA + 4.