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Special Filter Instructions
4-67Assembly Language Instructions
Figure 4–6. Setup and Execution of MSP50P614/MSP50C614 Filter Instructions,
N+1 Taps
Accumulators
0–15
th
bits of y
16–31
st
bits of y
32–47
th
bits of y
ACr
ACr+1
ACr+2
y[k] = Σ
m=0..N
h[m]x[k–m]
+
MultiplierPH MR
Past N samples,
x[k]
Coefficients, h[k]
k = 0..N
Data memory
(FIR/COR)
Program memory (FIRK/CORK)
sample_buf
coeff_array
ACr+1ACr+2 ACry =
For COR/CORK
ACrACr+1y =
For FIR/FIRK
TAG=1 for 2
nd
to last sample for
Circular buffer operation
+
Accumulators Pointer
Point to accumulator, ACrAn = ACn
Circular buffer operation only
Circular buffer length, –2NR5
sample_buf address
Rx
even
{R0,R2,R4,R6}
coeff_array address
DP
coeff_array address
Rx
even
+1
{R1,R3,R5,R7}
FIR/COR only
FIRK/CORK only
†
The value of y is stored in ACr and ACr+1 for FIR instruction (32-bit accumulation). COR instruction uses 48-bit accumulation
and includes accumulator ACr+2.
coeff_array
Coefficients, h[k]
k = 0..N