cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 140

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

5.0 Reassembly Coprocessor
5.4 Buffer Management
5-30
the RX_COUNTER[15:0] of the applicable channel. For proper operation of the
update interval function, buffers must be returned at the same time as credits are
returned.
return buffer credits independently from buffer usage, the CN8236 maintains a
separate read pointer into free buffer queues that return credits. This pointer name
is FORWARD, located in the free buffer queue base table entry. The host
determines the number of Bank 0 free buffer queues that return credits by setting
FWD_EN in the RSM_FQCTRL register.
When a write completes, the CN8236 begins processing firewall return credits on
that queue. The third word of each entry is read, and if FWD_VLD is set, a credit
is added to the VCC_INDEX indicated. The CN8236 continues to process credit
return entries until FWD_VLD is zero. Multiple free buffer queues might have
credit return entries outstanding at one time. The CN8236 processes the entries
according to the priority set in FWD_RND in the RSM_FQCTRL register. If
FWD_RND is a logic low, the CN8236 exhausts the credit returns on the highest
number active queue before proceeding to other queues. Otherwise, it services the
queues in round-robin order.
FORWARD read pointer to the first entry where credit is returned. Typically, this
is the first entry after the initial buffers placed on the queue.
Credits are returned to VCCs through Bank 0 free buffer queues. In order to
The CN8236 snoops writes to free buffer queues that return firewall credits.
Before the reassembly coprocessor is enabled, the host must initialize the
Mindspeed Technologies
ATM ServiceSAR Plus with xBR Traffic Management
™
28236-DSH-001-B
CN8236