Motorola MPC823e - Page 501

Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-47
DSP
COMMUNICATION
16
PROCESSOR MODULE
16.3.4.3.1 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
input sample is two 16-bit half-words (real and imaginary components). 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 each output is two 16-bit half-words (real and imaginary
components). The new output is stored in the address that follows the previous output.
16.3.4.3.2 FIR3 Function Descriptor. The FIR3 function descriptor bit table is described
below.
COEFFICIENTS INPUT SAMPLES REAL OUTPUT
(X=0)
COMPLEX OUTPUT
(X=1)
imag{C(0)} * * *
real{C(0)} * * *
imag{C(1)} imag {x(n-k+1)} * imag{Y(n-k+1)}
real{C(1)} real {x(n-k+1)} * real{Y(n-k+1)}
* * real {Y(n-K+1)} *
* imag {x(n-2)} * *
imag{C(k-1)} real{x(n-2)} * imag{Y(n-2)}
real{C(k-1)} imag{x(n-1)} real {Y(n-2)} real{Y(n-2)}
real{x(n-1)} real {Y(n-1)} imag{Y(n-1)}
imag{x(n)} real {Y(n)} real{Y(n-1)}
real{x(n)} imag{Y(n)}
real{Y(n)}
2K bytes M + 1 bytes N + 1 bytes N + 1 bytes
Figure 16-17. FIR3 Coefficients and Sample Data Buffers
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
OFFSET + 0
S RES W I Z IALL INDEX PC RES OPCODE
OFFSET + 2
I
OFFSET + 4
K
OFFSET + 6
CBASE
OFFSET + 8
M
OFFSET + A
XYPTR
OFFSET + C
N
OFFSET + E
RESERVED