stdx

Store Doubleword Indexed X-form

stdx RS,RA,RB

Stores a doubleword from a register to memory using an indexed address.

Details

Stores a doubleword (64 bits) from register RS to memory at the address formed by adding the contents of RA and RB. The effective address is calculated as (RA|0) + RB. No condition registers or status fields are modified by this instruction.

Pseudocode Operation

EA ← (RA|0) + RB
[EA] ← RS[0:63]

Programming Note

The stdx instruction is commonly used for storing a doubleword from a register into memory at an address derived from the sum of two registers. Ensure that RA and RB are correctly set to avoid incorrect memory addresses. This instruction operates in user mode and can raise exceptions if there's a protection fault or alignment error.

Example

stdx r3, r4, r5

Encoding

Binary Layout
62
0
RS
6
RA
11
RB
16
 
Format X-form
Opcode 0x7C00012A
Extension Base

Operands

  • RS
    Source General Purpose Register
  • RA
    Base Address General Purpose Register
  • RB
    Index General Purpose Register