Freescale Semiconductor StarCore SC140 - Manual (Page 485)

EXTRACT
SC140 DSP Core Reference Manual A-171
EXTRACT
Extract Signed Bit Field (DALU)
EXTRACT
Description
These operations extract a bit field from a source data register (Db) and place it in a destination data
register (Dn), right-aligned and sign-extended from the MSB of the extracted bit field. The extracted field
is a signed integer. If the offset is zero, this instruction can be used to sign-extend an arbitrary width signed
integer.
Status and Conditions that Affect Instruction
None.
Status and Conditions Changed by Instruction
Example
extract #$c,#$e,d2,d4
Operation Assembler Syntax
Db[(offset + width – 1):offset]
→ Dn[(width – 1):0]
Db[offset + width – 1]
→ Dn[39:width] (sign-extension)
width = #U6; offset = #u6 EXTRACT #U6,#u6,Db,Dn
{0
≤ U6 ≤ 40}{0 ≤ u6 ≤ 40}
{#U6+#u6
≤ 40}
width = Da[13:8]; offset = Da[5:0] EXTRACT Da,Db,Dn
{0
≤ Da[13:8] ≤ 40}
{0
≤ Da[5:0] ≤ 40}
{Da[13:8]+Da[5:0]
≤ 40}
EXTRACT #U6,#u6,Db,Dn
Uses two immediate unsigned 6-bit integers for the width (#U6) and offset (#u6).
EXTRACT Da,Db,Dn
Uses a supplemental data register (Da) for the width (bits 13–8) and the offset (bits 5–0).
Register Address Bit Name Description
Ln L Clears the Ln bit in the destination register.
Register/Memory Address Before After
immediate (width) $C
immediate (offset) $E
D2 $FF 8665 4321
L4:D4 $0:$00 0000 0000 $0:$FF FFFF F995