Motorola MPC8260 - Manual (Page 850)

29-70 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
Table 29-35 describes AAL5 RxBD Þelds.
Table 29-35. AAL5 RxBD Field Descriptions
Offset Bits Name Description
0x00 0 E Empty.
0 The buffer associated with this RxBD is full or data reception was aborted due to an
error. The core can read or write any Þelds of this RxBD. The CP does not use this BD
again while E remains zero.
1 The buffer associated with this RxBD is empty or reception is in progress. This RxBD
and its receive buffer are controlled by the CP. Once E is set, the core should not write
any Þelds of this RxBD.
1 Ñ Reserved, should be cleared.
2 W Wrap (Þnal BD in table)
0 This is not the last BD in the RxBD table of the current channel.
1 This is the last BD in the RxBD table of this current channel. After this buffer has been
used, the CP receives incoming data into the Þrst BD in the table. The number of RxBDs
in this table is programmable and is determined only by the W bit. The current table
cannot exceed 64 Kbytes.
3 I Interrupt
0 No interrupt is generated after this buffer has been used.
1 An Rx buffer event is sent to the interrupt queue after the ATM controller uses this buffer.
FCCE[GINTx] is set in the event register when INT_CNT reaches the global interrupt
threshold.
4 L Last in frame. Set by the ATM controller for the last buffer in a frame.
0 Buffer is not last in a frame.
1 Buffer is last in a frame. ATM controller writes frame length in DL and updates the error
ßags.
5 F First in frame. Set by the ATM controller for the Þrst buffer in a frame.
0 The buffer is not the Þrst in a frame.
1 The buffer is the Þrst in a frame.
6 CM Continuous mode
0 Normal operation.
1 The CP does not clear the empty bit after this BD is closed, allowing the associated
buffer to be overwritten automatically when the CP next accesses this BD.
7Р9 С Reserved, should be cleared.
10 CLP Cell loss priority. At least one cell associated with the current message was received with
CLP = 1. May be set at the last buffer of the message.
11 CNG Congestion indication. The last cell associated with the current message was received
with PTI middle bit set. CNG may be set at the last buffer of the message.
12 ABRT Abort message indication. The current message was received with Length Þeld zero.
13 CPUU CPCS-UU+CPI indication. Set when the CPCS-UU+CPI Þeld is non zero. CPUU may be
set at the last buffer of the message.
14 LNE Rx length error. AAL5 CPCS-PDU length violation. May be set only for the last BD of the
frame if the pad length is greater than 47 or less than zero octets.
15 CRE Rx CRC error. Indicates CRC32 error in the current AAL5 PDU. Set only for the last BD of
the frame.