ATM AAL2
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
32-30 Freescale Semiconductor

Table32-9 describes the CPS switch RxQD fields.

32.4.4.6 SWITCH Receive/Transmit Buffer Descriptor (RxBD)

The switch buffer structure consists of a BD table that points to data buffers. The RxBDs contain, apart

from the buffer pointer, the packet header, as shown in Figure32-19. The buffers contain the packet

payload. This BD is common to the receiver and the transmitter.

Table 3-11 describes the Switch RxBD fields.

0 7 8 11 12 13 14 15
Offset + 0x00 TX CID RBM PPD SubType
Offset + 0x02 TxQD Pointer

Figure 32-18. CPS Switch Rx Queue Descriptor

Table32-9. CPS Switch RxQD Field Descriptions

Offset Bits Name1
1 Boldfaced entries must be initialized by the user.
Description
0x00 0-7 TX CID Translation CID. The received CID is saved in a TX Queue with this new CID number.
8-11 Reserved, should be cleared during initialization.
12 RBM Receive buffer mask
0 Disable receive buffer interrupt
1 Enable receive buffer interrupt
13 PPD Partial packet discard
0 Normal mode
1 When a buffer-not-ready event causes a packet to be discarded, the remainder of the
SSSAR SDU is also discarded. This allows for better performance for switched
channels that implement SSSAR.
14-15 SubType Sublayer type. Should be 01 (CPS switched) for this descriptor.
00 CPS sublayer
01 CPS switched
10 SSSAR
11 Reserved
0x02 — TxQD
Pointer
Points to the TxQD into which the packets of this CID are stored and later sent.
0 1 2 3 4 5 6 7 8 15
Offset + 0x00 E/R 0 W I UP CPS Packet Header
Offset + 0x02 Packet Header (Receiver CC)
Offset + 0x04 Rx Data Buffer Pointer (RXDBPTR)
Offset + 0x06

Figure 32-19. Switch Receive/Transmit Buffer Descriptor