Figure 13-7.Insertion, Case 2. Source And Destination Accumulators Are The Same - Lucent Technologies DSP1617 Information Manual

Information Manual
April 1998
13.2 Software View
13.2.5 Insertion (continued)
Case 2. Case 2 is more complex. If aS is the same as aD in the instruction, aS is an implicit second source. The
field from the aS accumulator is moved over by an amount defined by the offset. The other bits outside of the field
come from the other accumulator aS.
Figure 13-7. Insertion, Case 2. Source and Destination Accumulators Are the Same
The instructions are as follows:
aD = insert (aS, IM16) Get field from immediate IM16 and insert.
aD = insert (aS, arM) Get field from arM register and insert.
For instance, for insertion instruction case 2,
let a0 = aS = aD = 0x0000000F
and a1 = aS = 0x00FAAABB
then the instruction
a0 = insert (a0, 0x0410)
results in
a0 = 0x00FFAABB
The eight flags (described
normal definitions, except LLV is true if WIDTH = 0 or if (WIDTH + OFFSET) > 36.
Lucent Technologies Inc.
DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
(continued)
BEFORE
aS = aD
SOURCE &
DESTINATION
ACCUMULATOR
AFTER
SOURCE 2
Section 13.2.2, Shifting
DRAFT COPY
aS
Operations) are set based on the value written into aD with their
Bit Manipulation Unit
WIDTH
OFFSET
5-4135
13-7