Motorola MPC823e - Page 508

Communication Processor Module
16-54 MPC823e REFERENCE MANUAL MOTOROLA
DSP
COMMUNICATION
16
PROCESSOR MODULE
16.3.4.5 FIR6–COMPLEX C, REAL X, AND COMPLEX Y. The FIR6 function implements
a basic FIR filter with k complex coefficients, real input samples, and complex output. The
input data is in a circular buffer with size M+1 and the output data is in a circular buffer with
size N+1.
16.3.4.5.1 Coefficients and Sample Data Buffers. The coefficients vector occupies k
pairs of 16-bit half-words (real and imaginary components) in memory and C(0) is stored in
the first location. The sample input buffer is a cyclic buffer containing M+1 bytes and each
sample is a 16-bit half-word. The new sample is stored in the address that follows the
previous sample. The output buffer is a cyclic buffer that contains N+1 bytes and the new
output is stored in the address that follows the previous output.
Figure 16-20. FIR6 Implementation Example
T
T
T
∑
X(N)
Y(N)
C(0)
C(1)
C(2)
C(K-1)
{REAL}
{COMPLEX}
{COMPLEX}
Yn () Cp () Xn p –()
p0=
k1
–
∑
=