oris

OR Immediate Shifted

oris RA, RS, UI

Performs a bitwise OR with a 16-bit immediate shifted left by 16 bits.

Encoding

Binary Layout

25

0:5

RS

6:10

RA

11:15

UI

16:31

 

Format D-form

Opcode 0x64000000

Extension Base

Operands

• RA
  Target Register
• RS
  Source Register
• UI
  Unsigned 16-bit Immediate

Example

oris r3, r4, 0xFFFF

// Set upper 16 bits.

Related

More in Base

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

Performs a bitwise OR between a general-purpose register and a 16-bit unsigned immediate value shifted left by 16 bits, storing the result in another register. This is a base category instruction used to set high-order bits with no condition register updates.

Operation

RA ← RS | (UI || 0x0000)

Programming Note

The oris instruction is commonly used to set specific bits in a register by ORing it with an immediate value. Be cautious of overflow if UI exceeds the upper limit, as it will be truncated. This instruction operates at user privilege level and does not generate exceptions under normal circumstances.