Communication Processor Module
16-28 MPC823e REFERENCE MANUAL MOTOROLA
DSP
COMMUNICATION
16
PROCESSOR MODULE
16.3.3.1 DATA REPRESENTATION. The inputs, coefficients, and outputs are represented
by 16-bit, fixed-point, 2’s complement numbers. A real number is represented by a single
16-bit half-word, as illustrated in Figure 16-8. Its value is between -1 (0x8000) to +1
(0x7FFF) and you must scale your data to fit this range. A complex number is represented
by a pair of 16-bit half-words—one word for the imaginary component and one for the real
component as shown in Figure 16-8. They must be scaled to fit in the -1 and +1 range.
Figure 16-8. DSP Function Descriptor Operation
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD S REAL FRACTION
BIT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
FIELD S IMAGINARY FRACTION
BIT 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
FIELD S REAL FRACTION
SYSTEM MEMORY
DUAL-PORT MEMORY
RECEIVE FD CHAIN
TRANSMIT FD CHAIN
INPUT, OUTPUT, AND COEFFICIENT
BUFFERS
RX CHAIN BASE
TX CHAIN BASE
DSP1
DSP2
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