stdu (Store Double Word with Update) instruction

Purpose

Store a doubleword of data from a general purpose register into a specified memory location. Update the address base.

Note: This instruction should only be used on 64-bit PowerPC® processors running a 64-bit application.

Syntax

Bits	Value
0 - 5	62
6 - 10	RS
11 - 15	RA
16 - 29	DS
30 - 31	0b01

PowerPC 64
stdu	RS, Disp(RA)

Description

The stdu instruction stores a doubleword in storage from the source general-purpose register (GPR) RS into the specified location in memory referenced by the effective address (EA).

DS is a 14-bit, signed two's complement number, which is sign-extended to 64 bits, and then multiplied by 4 to provide a displacement Disp. If GPR RA is not 0, the EA is the sum of the contents of GPR RA and Disp. If GPR RA is 0, then the EA is Disp.

If GPR RA = 0, the instruction form is invalid.

Parameters

Item	Description
RS	Specifies the source general-purpose register containing data.
Disp	Specifies a 16-bit signed number that is a multiple of 4. The assembler divides this number by 4 when generating the instruction.
RA	Specifies source general-purpose register for EA calculation.

Implementation

This instruction is defined only for 64-bit implementations. Using it on a 32-bit implementation will cause the system illegal instruction error handler to be invoked.