ZXTA.x

ZXTA.x

Zero Extension (AGU)

ZXTA.x

Operation

Assembler Syntax

 

rx[7:0] → Rx[7:0]; 0 → Rx[31:8]

ZXTA.B rx,Rx

 

0 → Rx[31:16]

ZXTA.W Rx

 

Description

These operations zero-extend an AGU source register (address or offset register, program counter, or stack pointer).

ZXTA.B rx,Rx

Copies bits [7:0] from a source AGU register (rx) to a 32-bit destination AGU register (Rx) and zero-extends bits [31:8] of Rx.

ZXTA.W Rx

Zero-extends bits [31:16] of Rx.

Status and Conditions that Affect Instruction

Register Address

Bit Name

Description

SR[18]

EXP

Determines which stack pointer is used when the stack pointer is an

 

 

operand. Otherwise, the instruction is not affected by SR.

Status and Conditions Changed by Instruction

None.

Example 1

zxta.b r3,n2

Register/Memory Address

R3

N2

BeforeAfter

$E4A6 5C8A

$0000 008A

Example 2

zxta.w r4

Register/Memory Address

R4

Before

$E4A6 5C8A

After

$0000 5C8A

A-430

SC140 DSP Core Reference Manual

Page 744
Image 744
Freescale Semiconductor SC140 specifications Zero Extension AGU, Zxta.b r3,n2, Zxta.w r4