user manual

MicroBlaze Processor Reference Guide www.xilinx.com 131

UG081 (v6.0) June 1, 2006 1-800-255-7778

Instructions

rted

Return from Exception

Description

Return from exception will branch to the location speciﬁed by the contents of rA plus the

IMM ﬁeld, sign-extended to 32 bits. The instruction will also enable exceptions after

execution.

This instruction always has a delay slot. The instruction following the RTED is always

executed before the branch target.

Pseudocode

PC ← (rA) + sext(IMM)

allow following instruction to complete execution

MSR[EE] ← 1

MSR[EIP] ← 0

ESR ← 0

Registers Altered

• PC

• MSR[EE]

• MSR[EIP]

• ESR

Latency

2 cycles

Note

Convention is to use general purpose register r17 as rA. This instruction requires that one

or more of the MicroBlaze parameters C_*_EXCEPTION are set to 1.

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.

rted rA, IMM

1 0 1 1 0 1 1 0 1 0 0 rA IMM

0 6 11 16 31