
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
63
Table 11 – Transmit Channel Descriptor Reference Table Fields
Field
Description
M
A copy of the M bit in the TD currently being read.
CE
A copy of the CE bit in the TD currently being read.
Last TD Pointer [13:0] Offset to the head of the last host-linked chain of TDs
to be read. (See Figure 14)
A
Indicates if this channel is active (i.e. provisioned). If
the channel is active, the A bit is set to logic 1. If the
channel is inactive, the A bit is set to logic 0.
D
Indicates whether the linked list of packets for this
channel is empty or not. If the D bit is set to logic 1,
the list is not empty and the current TD pointer field is
valid (i.e., it points to a valid TD). If the D bit is set to
logic 0, the list is empty and the current TD pointer field
is invalid.
Current TD Pointer
[13:0]
Offset to the TD currently being read.
Bytes To Tx[15:0]
The Bytes to Tx[15:0] bits are used to indicate the total
number of bytes that remain to be read in the current
buffer. Each access to the data buffer decrements this
value. A value of zero in this field indicates the buffer
has been completely read.
ABRT
A copy of the ABRT bit in the TD currently being read.
IOC
A copy of the IOC bit in the TD currently being read.
PiP
The Packet Transfer in Progress bit indicates that a
packet is currently being transmitted on this channel at
this priority level.
NA
Indicates that a ‘null abort’ is to be sent to the
downstream block when it next requests data on this
channel. The NA bit is set if a mal-formed TD is
encountered while searching down a host chain.
U
Indicates that a underflow has occurred on this
channel. This bit is set in response to an underflow
indication for the downstream THDL block and is
cleared when a TDR is written to the TDR Free Queue
(or to the free queue cache).