R

Chapter 4: MicroBlaze Instruction Set Architecture

rtid

Return from Interrupt

rtid

rA, IMM

1 0 1 1 0 1

1 0 0 0 1

rA

IMM

0

6

11

16

31

Description

Return from interrupt will branch to the location specified by the contents of rA plus the IMM field, sign-extended to 32 bits. It will also enable interrupts after execution.

This instruction always has a delay slot. The instruction following the RTID is always executed before the branch target. That delay slot instruction has interrupts disabled.

Pseudocode

PC (rA) + sext(IMM)

allow following instruction to complete execution MSR[IE] 1

Registers Altered

PC

MSR[IE]

Latency

2 cycles

Note

Convention is to use general purpose register r14 as rA.

A delay slot must not be used by the following: IMM, branch, or break instructions. This also applies to instructions causing recoverable exceptions (e.g. unalignement), when hardware exceptions are enabled. Interrupts and external hardware breaks are deferred until after the delay slot branch has been completed.

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UG081 (v6.0) June 1, 2006

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Xilinx EDK 8.2i manual Return from Interrupt Rtid RA, IMM, Msrie