R

Chapter 4: MicroBlaze Instruction Set Architecture

rtsd

Return from Subroutine

rtsd

rA, IMM

1 0 1 1 0 1

1 0 0 0 0

rA

IMM

0

6

11

16

31

Description

Return from subroutine will branch to the location specified by the contents of rA plus the IMM field, sign-extended to 32 bits.

This instruction always has a delay slot. The instruction following the RTSD is always executed before the branch target.

Pseudocode

PC (rA) + sext(IMM)

allow following instruction to complete execution

Registers Altered

PC

Latency

2 cycles

Note

Convention is to use general purpose register r15 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.

132

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UG081 (v6.0) June 1, 2006

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Xilinx EDK 8.2i manual Return from Subroutine Rtsd RA, IMM