lqarx

Load Quadword And Reserve Indexed

lqarx RTp, RA, RB

Loads a quadword from memory and reserves the location for conditional store.

Encoding

Binary Layout

31

0:5

RTp

6:10

RA

11:15

RB

16:20

276

21:30

0

31

 

Format X-form

Opcode 0x7C000228

Extension Base

Operands

• RTp
  Target Pair
• RA
  Base
• RB
  Index
• EH
  Hint operand

Example

lqarx r4, r4, r5

Registers Altered

RESERVE, RESERVE_LENGTH, RESERVE_ADDR

Related

More in Base

Reference

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

Description

For lqarx, the quadword in storage addressed by EA is loaded into an even-odd pair of GPRs. In Big-Endian mode, the even-numbered GPR is loaded with the doubleword from storage addressed by EA and the odd-numbered GPR is loaded with the doubleword addressed by EA+8. In Little-Endian mode, the even-numbered GPR is loaded with the byte-reversed doubleword from storage addressed by EA+8 and the odd-numbered GPR is loaded with the byte-reversed doubleword addressed by EA.

Operation

if RA = 0 then
    b ← 0
else
    b ← (RA)
EA ← b + (RB)
RESERVE ← 1
RESERVE_LENGTH ← 16
RESERVE_ADDR ← real_addr(EA)
RTp ← MEM(EA, 16)

Extended Mnemonics

Extended Mnemonic	Equivalent Instruction
lqarx

Programming Note

lqarx serves as both a basic and an extended mnemonic. The Assembler will recognize a lqarx mnemonic with four operands as the basic form, and a lqarx mnemonic with three operands as the extended form. In the extended form the EH operand is omitted and assumed to be 0.