Motorola MPC860 PowerQUICC User Manual page 929

36.11.4 FIR5ÐComplex C, Complex X, and Complex Y
Using the values provided in the parameter packet, the FIR5 implements a basic FIR Þlter,
shown in Figure 36-17, with complex coefÞcients, complex 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).
X(n)
{Complex}
36.11.4.1 FIR5 CoefÞcient, Input, and Output Buffers
The coefÞcient vector occupies K pairs of 16-bit entries (real and imaginary components)
in memory and C(0) is stored in the Þrst location. The input sample buffer is a circular
buffer containing (M+1) bytes. Each input sample is two 16-bit entries (real and imaginary
components) and the next sample is stored in the address that follows the previous sample.
The output buffer is a circular buffer that contains (N+1) bytes and the next output is stored
in the address that follows the previous output. See Table 36-13.
Table 36-13. FIR5 Coefficient, Input, and Output Buffers
CoefÞcients
imaginary{C(0)}
real{C(0)}
imaginary{C(1)}
real{C(1)}
*
*
imaginary{C(k-1)}
MOTOROLA
C(0)
{Complex}
å
T
C(1)
T
C(2)
T
C(kÐ1)
Figure 36-17. FIR5 Function
Input Samples
*
*
imaginary {x(n-k+1)}
real {x(n-k+1)}
*
*
imaginary {x(n-2)}
Chapter 36. Digital Signal Processing
Part V. The Communications Processor Module
Y(n)
{Complex}
k 1
Ð
å
Y n ( ) C p ( )X n p
=
p = 0
Complex Output, FD[X]=1
*
*
imaginary{Y(n-k+1)}
real{Y(n-k+1)}
*
*
imaginary{Y(n-2)}
( )
Ð
Real Output, FD[X]=0
*
*
Y(n-k+1)
*
*
Y(n-2)
Y(n-1)
36-15