RELEASED
PM7380 FREEDM-32P672
DATA SHEET
PMC-1990262
ISSUE 5
FRAME ENGINE AND DATA LINK MANAGER 32P672
Table 11 – Transmit Channel Descriptor Reference Table Fields
Field
Description
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.
ABRT
IOC
M
CE
A
A copy of the ABRT bit in the TD currently being read.
A copy of the IOC bit in the TD currently being read.
A copy of the M bit in the TD currently being read.
A copy of the CE bit in the TD currently being read.
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
[14:0]
Offset to the TD currently being read. (See Figure 15)
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.
Host TD Pointer [14:0] A copy of the Host Next TD Pointer field of the TD
currently being read, i.e. a pointer to the next TD in the
chain currently being read. (See Figure 15)
DMA Current
The DMA Current Address [31:0] bits hold the address
of the next dword in the current buffer. This field is
incremented on each access to the buffer.
Address[31:0]
U
Indicates that an underflow has occurred on this
channel. This bit is set in response to an underflow
indication for the downstream THDL672 block and is
cleared when a TDR is written to the TDR Free Queue
(or to the free queue cache).
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
73
PMC [ PMC-SIERRA, INC ]
