or

Logical OR

OR r/m, r

Performs bitwise OR.

Details

The Logical OR instruction performs bitwise OR.

Pseudocode Operation

DEST <- DEST OR SRC
// Flags affected: SF, ZF, PF (OF=CF=0)

Example

OR EAX, 1 ; Set lowest bit OR EAX, EAX ; Check if EAX is zero (sets ZF)

Encoding

Binary Layout
09
+0
 
Format Legacy
Opcode 09
Extension Base

Operands

  • dest
    Register/Memory
  • src
    Register