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MT90500
149
7.4.2
Memory Structure Summary
Table 103 - Summary of External Memory Structures
External
Memory
Structure
SIze
(in bytes)
Start on Boundary
Do not cross boundary
Notes
TX Circular
Buffer Control
Structure
Min: 256
Max: 4096
Control structure must start
on
512-byte
boundary:
x0 0000 0000
Register 6040h:
TXCBCSBASE = bits<20:9>
of TX Circular Buffer Control
Structure Base Address.
Control structures cannot
cross an
8192-byte (8K)
boundary
x0 0000 0000 0000
Therefore, to ensure that
structure never crosses this
boundary, start structure on
a boundary equal to the
structure size.
Structure size = # of
entries * 2 bytes/entry.
TX Circular
Buffers
64
(per TDM
channel
transmitted)
First buffer must start on a
512-byte
boundary:
x0 0000 0000
Register 6044h:
TXCBBASE = bits<20:9> of
TX Circular Buffer Base
Address.
Each control structure must
start on a
16-byte
boundary:
Each subsequent buffer
automatically starts on
next 64-byte boundary.
Transmit
Control
Structures
Min: 14
Max: 256
(per VC)
x 0000
Register 2040h:
TXBASE = bits<20:16> of
Transmit Control Structure
Base Address.
The address in the scheduler
provides bits<15:4> of
address.
Each scheduler must start on
a
512-byte
boundary:
Control structures cannot
cross a
256-byte
boundary
x 0000 0000
Transmit
Event
Schedulers
Min: 16
Max: 16K
(per scheduler
- up to 3 can
be configured)
x0 0000 0000
Register 2010h/2020h/
2030h:
SBASE = bits<20:9> of
Scheduler Base Address.
Min. Size = 1 frame * 8
entries/frame * 2 bytes/
entry.
Typ. Size = 47 frames *
16 entries/frame * 2
bytes/entry.
Max. Size = 256 frames *
32 entries/frame * 2
bytes/entry.
Min. Size = 2^(8 + 2) =
1024.
Look-Up-
Table
Min: 1024
Max: 128K
The look-up table must start
on a boundary equal to the
table size
= 2^(M+N+2)
= #-of-entries * 4 bytes
Register 401Eh:
LUTBASE = bits<20:5> of
pointer to start of look-up
table.
Register 4010h:
M and N = number of LSBs
from VPI and VCI,
respectively, to be used in
address.
Max. Size = 2^(15 + 2) =
131072 = 128K.
Requires external
memory allocation of
2^(M + N + 2) bytes.