Xilinx MicroBlaze Reference Manual page 278

rtsd Return from Subroutine
rA, IMM
rtsd
1 0 1 1 0 1 1 0 0 0 0
0
6
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
←
(rA) + sext(IMM)
PC
allow following instruction to complete execution
Registers Altered
• PC
Latency
• 1 cycle (if successful branch prediction occurs)
• 2 cycles (with Branch Target Cache disabled)
• 3 cycles (if branch prediction mispredict occurs with
• 7-9 cycles (if a branch prediction mispredict occurs with
Notes
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. Interrupts and
external hardware breaks are deferred until after the delay slot branch has been completed.
MicroBlaze Processor Reference Guide
UG984 (v2018.2) June 21, 2018
Chapter 5: MicroBlaze Instruction Set Architecture
rA
11 16
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IMM
=0)
C_AREA_OPTIMIZED
C_AREA_OPTIMIZED
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31
=2)
279