RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 132

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

5.0 Reassembly Coprocessor
5.4 Buffer Management
5.4.9.2 Halting Time-out
5.4.10 Virtual FIFO Mode
5-28
5.4.9.5 Time-out Period
5.4.9.4 Reassembly
5.4.9.3 Timer Reset
5.4.10.2 Operation
Time-out Condition
5.4.10.3 Errors
5.4.10.1 Setup
Calculation
Processing
on the current VCC. The RS8234 follows the procedure described in
Section
To halt time-out processing, the host “must” set the TO_LAST bit to one, in the
RSM VCC Table entry for the last VCC_INDEX that the host wishes to have
enabled for time-out processing. When the RS8234 detects this bit set to one, it
halts time-out processing.
but the VCC will not be checked for a time-out condition. The RS8234 will
simply increment TO_VCC_INDEX and compare it to RSM_TO_CNT. If they
are equal, TO_VCC_INDEX is reset to zero and the full time-out processing is
re-enabled.
The RS8234 reassembly time-out process increments the CUR_TOCNT value. If
it reaches a threshold value, a time-out condition has occurred. In AAL5 and
AAL0, PTI termination modes, the reception of a non-EOM cell will reset the
counter.
The RS8234 reports reassembly time-out conditions via the VCC’s reassembly
status queue. The TO bit in the STATUS field of the status queue entry will be set
to one. In Message Mode, the BD_PNTR will point to the beginning of the partial
buffer descriptor chain. In Streaming Mode, the BD_PNTR will point to the last
buffer descriptor in the chain. The only other valid fields in the status queue entry
will be VCC_INDEX and VLD.
to begin accepting a CPCS-PDU.
The following equation determines the time-out period of a VCC.
VCCs which require time-out processing.
This mode provides a logical FIFO port for cell data to host memory. Its principal
use is for AAL0 CBR voice traffic.
To enable this mode on any channel, set FIFO_EN in the RSM VCC Table to a
logic high. The user initializes the CBUFF_PNTR field in the RSM VCC Table to
the address of the FIFO port. The channel should also be configured for AAL0
fixed length termination mode, with a termination length of one cell.
Whenever a buffer is required during reassembly in this mode, the
CBUFF_PNTR address is used without accessing the free buffer queue.
synchronization between status entries and cells in the FIFO buffer under FIFO
buffer overflow conditions.
When the FIFO port is on the PCI bus, the CBUFF_PNTR address must be on a
64-byte boundary, and a decode of any address in the 64-byte block will access
If CUR_TOCNT = TERM_TOCNTx, then a time-out condition has occurred
When time-out processing is halted, the time-out process will still be activated,
Once status has been reported, the RS8234 re-initializes the VCC Table entry
RSM_TO_CNT must be greater than or equal to the maximum number of
No status entries are written in this mode because there is no way to maintain
5.4.9.4.
Mindspeed Technologies
Period = SYSCLK period x RSM_TO_PER x RSM_TO_CNT x
TERM_TOCNTx
ATM ServiceSAR Plus with xBR Traffic Management
™
28234-DSH-001-B
RS8234