Sxt.x, Sign-extension (dalu), Description – Freescale Semiconductor StarCore SC140 User Manual
Page 714: Status and conditions that affect instruction, Example 2, Operation assembler syntax
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SC140 DSP Core Reference Manual
SXT.x
SXT.x
Sign-Extension (DALU)
SXT.x
Description
These operations sign-extend a data register. The sign bit (bit 7 in a byte, bit 15 in a word, and bit 31 in a
long word) is copied to the upper bits in a 40-bit data register.
Status and Conditions that Affect Instruction
None.
Status and Conditions Changed by Instruction
Example 1
sxt.b d3,d0
Example 2
sxt.w d3,d2
Operation
Assembler Syntax
Da[7:0]
→ Dn[7:0]; Da[7] → Dn[39:8]
SXT.B Da,Dn
Da[15:0]
→ Dn[15:0]; Da[15] → Dn[39:16]
SXT.W Da,Dn
Dn[31]
→ Dn[39:32]
SXT.L Dn
SXT.B Da,Dn
Sign-extends a byte from a source data register (Da[7:0]) into a destination data register (Dn).
SXT.W Da,Dn
Sign-extends a word from a source data register (Da[15:0]) into a destination data register (Dn).
SXT.L Dn
Sign-extends a long word from a source data register (Dn[31:0]) into a destination data register (Dn).
Register Address
Bit Name
Description
Ln
L
Clears the Ln bit in the destination register.
Register/Memory Address
Before
After
D3
$FF FE34 A086
L0:D0
$0:$FF FFFF FF86
Register/Memory Address
Before
After
D3
$00 0000 7056