cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 135

• Manufacturer Part Number: cn8237
• Description: Atm Oc-12 Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
28237-DSH-001-C
5.6.1.2 Operation
5.6.1.1 Setup
At system initialization, set up the following fields in each of the status queue
base table entries:
the VLD bit to a logic low.
The reassembly coprocessor normally writes a status queue entry when a
complete CPCS-PDU has been reassembled. It also writes a status queue entry for
each received OAM cell.
bit in the entry to a logic high and increments the WRITE pointer in the status
queue base table entry for that status queue.
READ pointer for that status queue. It reads only the VLD bit at first before
reading any other word to maintain data coherency.
queue entry, increments the host READ counter, and resets the VLD bit to a logic
low. The host also periodically writes the READ counter value to the READ_UD
field in the status queue base table entry for that queue.
completion of a CPCS-PDU. Optionally, a status entry can be written at both the
beginning and end of a message, to allow the host to initiate protocol header
processing in advance of receiving the complete message. The host can then
traverse the linked cell buffers to collect the complete CPCS-PDU.
coprocessor writes an additional status queue entry at the completion of the first
buffer of a CPCS-PDU. This status queue entry is delineated by the BOM bit set
and the EOM bit cleared. This allows the host to begin packet processing before
reception of the complete CPCS-PDU. In this case only the BD_PNTR and
VCC_INDEX fields are valid in that status queue entry.
activates Streaming Mode for that channel. In this mode, the RSM coprocessor
writes a status entry for each completed buffer. The BD_PNTR field in the status
entry points to the corresponding buffer descriptor for that single buffer. Only the
last status entry for that CPCS-PDU, with EOM bit a logic high, contains valid
status data for that PDU.
queues.
• Write the base address of the corresponding status queue in the
• Initialize the WRITE and READ_UD fields to 0s.
• Set the SIZE field for the size of the corresponding status queue.
In addition, initialize each status queue entry in all 32 status queues by setting
Initialize the READ pointers to 0 for each status queue.
Each time the RSM coprocessor writes a status queue entry, it sets the VLD
When the host processes the status queue, it reads entries based on the host
When the host finds the VLD bit set to a logic high, it processes the status
When in Message Mode, the RSM coprocessor writes a status entry at the
If the BINTR bit in the RSM VCC table entry is a logic high, the RSM
The STM_MODE bit in the RSM VCC table, being set to a logic high,
Refer to
BASE_PNTR field.
Mindspeed Technologies
Chapter
2.0, for more detailed information on the operation of status
™
5.0 Reassembly Coprocessor
5.6 Status Queue Operation
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