Assembler Language Reference

eciwx (External Control In Word Indexed) Instruction

Purpose

Translates the effective address (EA) to a real address, sends the real address to a controller, and loads the word returned by the controller into a register.

Note

The eciwx instruction is defined only in the PowerPC architecture and is an optional instruction. It is supported on the PowerPC 601 RISC Microprocessor, PowerPC 603 RISC Microprocessor, and PowerPC 604 RISC Microprocessor.

Syntax

Bits	Value
0-5	31
6-10	RT
11-15	RA
16-20	RB
21-30	310
31	/

eciwx

RT, RA, RB

Description

The eciwx instruction translates EA to a real address, sends the real address to a controller, and places the word returned by the controller in general-purpose register RT. If RA = 0, the EA is the content of RB, otherwise EA is the sum of the content of RA plus the content of RB.

If EAR(E) = 1, a load request for the real address corresponding to EA is sent to the controller identified by EAR(RID), bypassing the cache. The word returned by the controller is placed in RT.

Notes:

EA must be a multiple of 4 (a word-aligned address); otherwise, the result is boundedly undefined.
The operation is treated as a load to the addressed byte with respect to protection.

Parameters

RT	Specifies target general-purpose register where result of operation is stored.
RA	Specifies source general-purpose register for operation.
RB	Specifies source general-purpose register for operation.

Related Information

ecowx (External Control Out Word Indexed) Instruction.

Processing and Storage.