
8201, 8202, 8203, 8204 Acceleration Processor Data Sheet, DS-0157-05
Page 117
Exar Confidential
5.3.4
Channel Manager Result Buffer
The Result Buffer is used to temporarily store the destination data generated by the
processing engines. Unlike source data, destination data is stored into the result buffer in
the order that the commands complete and is fetched using the same sequence, therefore
it mimics a FIFO.
The size of the write request payload must not exceed the parameter max_payload_size.
The host software sets this parameter during initialization and is typically set to 128 bytes.
If the result buffer is 1KB deep, it can accommodate 8 TLPs.
The result buffer is implemented as a dual-port 1K-byte memory. The data bus width is 72-
bits (64 bits of data and 8 bits of ECC).
Note: The 820x supports a maximum payload size, max_payload_size, of 128, 256 or 512
bytes. If the host configures the max read request size to 1KB or 2KB, the 820x will still
send 512B read requests over the PCIe interface.
5.3.5
Channel Manager Data Process Controller
The Data Process Controller (DPC) controls the data process flow and interface with all
processing engines. The main functions of the Data Process Controller are:
Separate the information bus from the source buffer, and feed the information bus
field to the processing engines
Read and align the data from the source buffer, and feed the source data to
processing engines
Verify the Key CRC if the command uses an the key
For encode operations, append a CRC to the source data or verify the CRC of input
data
For decode operations, verify the data CRC
Read the result data from the processing engines; align and write the data into the
result buffer
Control the encode and decode data flow
5.4 PKP Manager
The PKP Manager controls the flow of fetching instructions and operand data from host
memory to the PKP engine, and the flow of transmitting the calculated results from the PKP
engine to host memory.