
IBM2520L8767
IBM Processor for ATM Resources
ATM Transmit Buffer Segmentation (SEGBF)
Page 250 of 553
atmrm.chapt05.01
08/27/99
11.5: SEGBF Invalid LCD Register
This register provides feedback to the program when the segmentation logic detects an invalid LCD. If multi-
ple invalid LCDs are being processed, this register will contain the address of the last one that was processed
by the segmentation logic. To clear this condition for LCDs being processed by the cell scheduler it is
suggested that the program write X’FFFFFFFF’ to the segmentation pointer in the indicated LCD. This will
cause the segmentation logic to terminate cell transmission on the next opportunity and cause the cell sched-
uler to clean up and go on to the next buffer indicated in the LCD. There are several invalid LCD situations
that the segmentation logic checks for: The first is the LCD address not being on the correct boundary. For
example, if the chip is configured to have all LCDs on 128-byte boundaries and a LCD is encountered that is
not on a 128-byte boundary. Another invalid condition is when the transmit length configured in the LCD plus
the offset in the LCD when added together exceed the maximum overall packet size configured in the chip. It
is up to the program to determine which of the possible conditions caused the error to be reported.
Length
32 bits
Type
Read/Write
Address
XXXX 1418
Power On Value
X’00000000’
Restrictions
None
Detected LCD Error Address
A
S
I
T
B
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Bit(s)
Description
31-7
These bits contain the 32-bit address of the LCD detected to be in error.
6-4
Always read as zeros.
3
When set, this bit indicates that an LCD has been encountered that requires a larger number of eight-byte words from the
VCI than the current value configured in the SEGBF maximum LCD size register.
2
When set, this bit indicates an LCD containing an invalid AAL-type field was detected.
1
When set, this bit indicates a transmit length error was detected.
0
When set, this bit indicates that a bad sync byte was detected in an MPEG-2 transport stream packet.