lwat

Load Word Atomic

lwat RT,RA,FC

Loads a word from memory atomically.

Details

Loads a 32-bit word from memory at an address computed from RA with atomic semantics determined by function code FC. The loaded value is placed in GPR RT. This instruction requires alignment and may be restricted to hypervisor mode depending on FC value.

Pseudocode Operation

EA ← RA
RT ← [EA]
# Atomic load with fence behavior determined by FC

Programming Note

EA must be a multiple of 4, and the portion of mem(EA-4,12) accessed by the instruction must be contained within an aligned 32-byte block of storage. If either of these requirements is not satisfied, the system alignment error handler is invoked.

Example

lwat r3, r4, fc

Encoding

Binary Layout
18
0
LI
6
AA
30
LK
31
 
Format X-form
Opcode 0x7C00048C
Extension Base

Operands

  • RT
    Target General Purpose Register
  • RA
    Source General Purpose Register
  • FC
    Function Code