slw or sl (Shift Left Word) Instruction

Assembler Language Reference

slw or sl (Shift Left Word) Instruction

Purpose

Rotates the contents of a general-purpose register to the left by a specified number of bits and places the masked result in another general-purpose register.

Syntax

PowerPC
slw	RA,RS,RB
slw.	RA,RS,RB

POWER
sl	RA,RS,RB
sl.	RA,RS,RB

Description

The slw and sl instructions rotate the contents of the source general-purpose register (GPR) RS to the left N bits, where N is the shift amount specified in bits 27-31 of GPR RB, and store the logical AND of the rotated word and the generated mask in GPR RA.

Consider the following when using the slw and sl instructions:

If bit 26 of GPR RB is 0, then a mask of 32-N ones followed by N zeros is generated.
If bit 26 of GPR RB is 1, then a mask of all zeros is generated.

The slw and sl instructions each have two syntax forms. Each syntax form has a different effect on Condition Register Field 0.

Syntax Form	Overflow Exception (OE)	Fixed-Point Exception Register	Record Bit (Rc)	Condition Register Field 0
slw	None	None	0	None
slw.	None	None	1	LT,GT,EQ,SO
sl	None	None	0	None
sl.	None	None	1	LT,GT,EQ,SO

The two syntax forms of the slw instruction, and the two syntax forms of the sl instruction, never affect the Fixed-Point Exception Register. If the syntax form sets the Record (Rc) bit to 1, these instructions affect the Less Than (LT) zero, Greater Than (GT) zero, Equal To (EQ) zero, and Summary Overflow (SO) bits in Condition Register Field 0.

Parameters

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

Examples

The following code rotates the contents of GPR 4 to the left by 15 bits and stores the result of ANDing the rotated data with a generated mask in GPR 6:
```
# Assume GPR 5 contains 0x0000 002F.
# Assume GPR 4 contains 0xFFFF FFFF.
slw 6,4,5
# GPR 6 now contains 0x0000 0000.
```
The following code rotates the contents of GPR 4 to the left by 5 bits, stores the result of ANDing the rotated data with a generated mask in GPR 6, and sets Condition Register Field 0 to reflect the result of the operation:
```
# Assume GPR 4 contains 0xB004 3000.
# Assume GPR 5 contains 0x0000 0005.
slw. 6,4,5
# GPR 6 now contains 0x0086 0000.
# Condition Register Field 0 now contains 0x4.
```

Related Information

Fixed-Point Processor .

Fixed-Point Rotate and Shift Instructions .