ZXT.x

ZXT.x

Zero Extension (DALU)

ZXT.x

Operation

 

Assembler Syntax

 

Da[7:0] → Dn[7:0]; 0 → Dn[39:8]

 

ZXT.B Da,Dn

 

Da[15:0] → Dn[15:0]; 0 → Dn[39:16]

ZXT.W Da,Dn

 

0 → Dn[39:32]

 

ZXT.L Dn

 

Description

These operations zero-extend a data register.

ZXT.B Da,Dn

Copies bits [7:0] from a source data register (Da) to a 40-bit destination data register (Dn) and zero-extends bits [39:8] of Dn.

ZXT.W Da,Dn

Copies bits [15:0] from a source data register (Da) to a 40-bit destination data register (Dn) and zero-extends bits [39:16] of Dn.

ZXT.L Dn

Zero-extend a long word from bit 32 through the remaining upper bits in a 40-bit data register (Dn).

Status and Conditions that Affect Instruction

None.

Status and Conditions Changed by Instruction

Register Address

Bit Name

Description

Ln

L

Clears the Ln bit in the destination register.

Example 1

zxt.b d2,d5

Register/Memory Address

D2

L5:D5

Example 2

zxt.w d3,d6

Register/Memory Address

D3

Before

$00 46EA 8BE8

Before

$FF A836 5EC4

After

$0:$00 0000 00E8

After

A-428

SC140 DSP Core Reference Manual

Page 742
Image 742
Freescale Semiconductor SC140 specifications Zero Extension Dalu, Zxt.b d2,d5, Zxt.w d3,d6