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MicroBlaze Processor Reference Guide
UG081 (v14.7)
Chapter 5:
MicroBlaze Instruction Set Architecture
rtsd
Return from Subroutine
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
•
1 cycle (if successful branch prediction occurs)
•
2 cycles (with Branch Target Cache disabled)
•
3 cycles (if branch prediction mispredict occurs)
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. Interrupts and
external hardware breaks are deferred until after the delay slot branch has been completed.
rtsd
rA, IMM
1 0 1 1 0 1 1 0 0 0 0
rA
IMM
0
6
1
1
1
6
3
1