Atm Exceptions - Freescale Semiconductor MPC850 User Manual

Table 37-3 describes the RCT fields.
CT Offset Bits
0x00 0 FHNT
1-7 —
8 HEC
9 CLP
10 CNG
11 INF
0x00 12 CNGI
13 CDIS
Receive and Transmit Connection Tables (RCTs and TCTs)
Table 37-3. RCT Field Descriptions
Name
Frame hunt mode. Indicates that this channel has had a busy exception or a
restart and is currently in frame hunt mode. In frame hunt mode the CP
discards all received cells until a new frame is started (indicated by the CPI bit
of the last cell header). FHNT is cleared by the user during initialization, and is
modified accordingly by the CP thereafter.
0 Not in frame hunt mode
1 In frame hunt mode
Reserved, should be cleared.
Header error control indication (serial ATM only). Used internally by the CP,
RCT[HEC] indicates that a HEC error has been detected in at least one cell of
the current frame.
For AAL5, this bit is set as soon as a cell of the current frame is determined to
have a HEC error. At the end of the frame, this bit is copied to the last
RxBD[HEC] of the frame. For AAL0, this bit is copied to the RxBD[HEC] for
each cell.
0 No HEC error has been detected.
1 A HEC error has been detected.
Cell loss priority indication (AAL5 only). Used internally by the CP, RCT[CLP]
indicates that at least one low priority cell has arrived as part of the current
AAL5 frame. This bit is set as soon as a cell of the current frame is determined
to have a CLP bit set in its header. At the end of the frame, this bit is copied to
the last RxBD[CLP] of the frame. For AAL0 channels, the CLP indication is
available in the cell header in the data buffer.
0 No low priority cells have arrived in the current frame.
1 A low priority cell has arrived during the current frame.
CNG—Congestion (AAL5 only). Used internally by the CP, RCT[CNG]
indicates that congestion has been reported in the last cell of the current frame.
RCT[CNG] is set only if the last cell of the current AAL5 frame has arrived with
the PTI[EFCI] bit set in its header. At the end of the frame, this bit is copied to
the last RxBD[CNG] of the frame.
0 No congestion has been reported.
1 Congestion has been reported.
In frame. The receiver sets RCT[INF] when a new frame starts and clears it
when the frame ends. This bit is used internally.
0 Idle state. No buffer is open for this channel.
1 Receiving. The receiver is in the middle of a frame; a receive buffer is open.
CNGI (AAL5 only)- Congestion interrupt. This bit enables interrupts when the
SAR layer detects a cell's PTI[EFCI] bit is set.
0 Disable congestion interrupts. Congestion is indicated in the last
RxBD[CNG] of the frame.
1 Enable congestion interrupts. An interrupt entry is added to the interrupt
queue if PTI[EFCI] is set in a received cell. See Chapter 41, "ATM
Exceptions."
Channel disable status. Set by the
RESTART RECEIVE
0 The channel is enabled to receive cells.
1 The channel is disabled. Cells addressed to this channel are discarded.
Note that the user should not modify this bit directly; that is, the
and
RESTART RECEIVE
However, CDIS should be cleared during initialization.
Chapter 37. Buffer Descriptors and Connection Tables
Description
STOP RECEIVE
command.
commands should be used to control the CDIS bit.
command; cleared by the
STOP RECEIVE