Specifications

Usage
The previous register set is specified by status.PRS. By default,
status.PRS indicates the register set in use before an exception,
such as an external interrupt, caused a register set change.
To read from an arbitrary register set, software can insert the
desired register set number in status.PRS prior to executing
rdprs.
If shadow register sets are not implemented on the Nios II core,
rdprs is an illegal instruction.
Exceptions
Supervisor-only instruction
Illegal instruction
Instruction Type
I
Instruction Fields
A = Register index of operand rA
B = Register index of operand rB
IMM16 = 16-bit signed immediate value
Bit Fields
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
A B IMM16
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
IMM16 0x38
ret
Instruction
return from subroutine
Operation
PC ← ra
Assembler Syntax
ret
Example
ret
Description
Transfers execution to the address in ra.
Usage
Any subroutine called by call or callr must use ret to return.
Exceptions
Misaligned destination address
Instruction Type
R
Instruction Fields
None
NII51017
2015.04.02
ret
8-67
Instruction Set Reference
Altera Corporation
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