Figure 4-6.Case 1. Source As And Destination Accumulators Different; Figure 4-7.Case 2. Source As And Ad Destination Accumulators The Same - Lucent Technologies DSP1617 Information Manual

Information Manual
April 1998
4.5 Instruction Set
4.5.7 BMU Instructions (continued)
aD = insert (aS, IM16)
aD = insert (aS, arM)
aS
aS, aD
Figure 4-6. Case 1. Source aS and Destination Accumulators Different
Figure 4-7. Case 2. Source aS and aD Destination Accumulators the Same
Lucent Technologies Inc.
DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
(continued)
Case 1—source and destination are different: The low-order bit field of width W from
the source accumulator is placed at a location in the destination accumulator deter-
mined by the OFFSET. The unaffected bits in the destination accumulator are
unchanged. Flags are set based on the value written to aD.
Case 2—the source and destination accumulators are the same: The insert field is
moved from its original location to a new location determined by the OFFSET. The
remaining bits are filled with the corresponding bits from the other accumulator. For
example, the instruction a0 = insert(a0, ar1) moves a bit field in a0 to a new location
in a0. The bits outside of the bit field are filled with the corresponding bits from a1.
Flags are set based on the value written to aD, a0 in this case.
The width and OFFSET are defined as in the extract instruction: either in an immedi-
ate IM16 or in an arM register.
SOURCE
ACCUMULATOR
SOURCE 2 &
DESTINATION
ACCUMULATOR
BEFORE
aS = aD
SOURCE &
DESTINATION
ACCUMULATOR
AFTER
SOURCE 2 aS
DRAFT COPY
WIDTH
SPECIFIED IN IMMEDIATE
OR arM
OFFSET
WIDTH
OFFSET
Instruction Set
5-4153
5-4154
4-33