18. Extend Sign Word X-form (extsw/EXTSW)

extsw RA,RS (Rc=0)
extsw. RA,RS (Rc=1)

31 RS RA /// 986 Rc
0  6  11 16  21  31

s <- (RS)32
RA32:63 <- (RS)32:63
RA0:31 <- 32s
(RS)32:63 are placed into RA32:63. RA0:31 are filled with
a copy of (RS)32.

Special Registers Altered:
CR0 (if Rc=1)

AIX 6.1:  

extsw (Extend Sign Word) instruction

Purpose

Copy the low-order 32 bits of a general purpose register into another general purpose register, and sign extend the fullword to a doubleword in size (64 bits).

Syntax

Bits	Value
0-5	31
6-10	S
11-15	A
16-20	00000
21-30	986
31	Rc

PowerPC®
extsw	RA, RS (Rc=0)
extsw.	RA, RS(Rc=1)

Description

The contents of the low-order 32 bits of general purpose register (GPR) RS are placed into the low-order 32 bits of GPR RA. Bit 32 of GPR RS is used to fill the high-order 32 bits of GPR RA.

Other registers altered:

• Condition Register (CR0 field):
  Affected: LT, GT, EQ, SO (if Rc = 1)
• XER:
  Affected: CA

Parameters

Item	Description
RA	Specifies the target general purpose register for the result of the operation.
RS	Specifies the source general purpose register for the operand of instruction.

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.