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Branch Using an Interrupt Return Pointer B IRP
3-73 Instruction SetSPRU733
Branch Using an Interrupt Return Pointer
B IRP
Syntax B (.unit) IRP
.unit = .S2
Compatibility C62x, C64x, C67x, and C67x+ CPU
Opcode
31 29 28 27 23 22 18 17 13 12 11 6 5 4 3 2 1 0
creg z dst 0 0 1 1 0 0 0 0 0 0 x 0 0 0 0 1 1 1 0 0 0 s p
3 1 5 1 1 1
Opcode map field used... For operand type... Unit
src2 xsint .S2
Description IRP is placed in the program fetch counter (PFC). This instruction also moves
the PGIE bit value to the GIE bit. The PGIE bit is unchanged.
If two branches are in the same execute packet and are both taken, behavior
is undefined.
Two conditional branches can be in the same execute packet if one branch
uses a displacement and the other uses a register, IRP, or NRP. As long as only
one branch has a true condition, the code executes in a well-defined way.
Execution if (cond) IRP
→ PFC
else nop
Notes:
1) This instruction executes on .S2 only. PFC is the program fetch counter.
2) Refer to the chapter on interrupts for more information on IRP, PGIE, and
GIE.
3) The execute packets in the delay slots of a branch cannot be interrupted.
This is true regardless of whether the branch is taken.
4) See section 3.5.2 on page 3-18 for information on branching into the
middle of an execute packet.