Zxta.x, Zero extension (agu), Description – Freescale Semiconductor StarCore SC140 User Manual
Page 744: Example 1, Example 2, Operation assembler syntax
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SC140 DSP Core Reference Manual
ZXTA.x
ZXTA.x
Zero Extension (AGU)
ZXTA.x
Description
These operations zero-extend an AGU source register (address or offset register, program counter, or stack
pointer).
Status and Conditions that Affect Instruction
Status and Conditions Changed by Instruction
None.
Example 1
zxta.b r3,n2
Example 2
zxta.w r4
Operation
Assembler Syntax
rx[7:0]
→ Rx[7:0]; 0 → Rx[31:8]
ZXTA.B rx,Rx
0
→ Rx[31:16]
ZXTA.W Rx
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.
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.
Register/Memory Address
Before
After
R3
$E4A6 5C8A
N2
$0000 008A
Register/Memory Address
Before
After
R4
$E4A6 5C8A
$0000 5C8A