RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 109

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
Figure 5-4. Programmable Block Size Alternate Direct Index Method
Table 5-1. Programmable Block Size Values for Direct Index Lookup
28234-DSH-001-B
Block Size for VCC Table/
5.2.2.1 Programmable
VCI_IT_BLK_SZ
Base Register (16)
Value of
000
001
010
011
100
101
110
VCI Index Table
VPI
Value
of
x
0
1
2
3
4
5
6
VPI Index Table
VCI_IT_PNTR
Some users might have a requirement or desire to limit the amount of memory
allocated to VPI/VCI channel lookup. To enable this, the RS8234 provides the
user with the choice of enabling an alternative scheme for the memory allocation
and table handling involved in the Direct Index Lookup mechanism. In this
scheme, the user programs the size of the memory block of RSM VCC Table
entries for all VCI Index table entries, to fit a range of 1–64 entries, instead of the
default 64 entries.
amount of memory space set aside for RSM VCCs, the total memory space
required for VCC allocation can be substantially lessened.
to a logic high. The SAR will thus allocate block memory for VCC entries per
VCI, based on the value entered in VCI_IT_BLK_SZ (RSM_CTRL1).
Figure 5-4
values for the number of VCI Index Table and VCC table entries per VCI.
Portion of Cell’s
VCI Index Table
Each RSM VCC entry requires 12 words of memory. By thus limiting the
To enable this scheme, set EN_PROG_BLK_SZ in the RSM_CTRL1 register
The data structures that facilitate this scheme are illustrated in
Table 5-1
VCI[15:0]
VCI[15:1]
VCI[15:2]
VCI[15:3]
VCI[15:4]
VCI[15:5]
VCI[15:6]
VCI
Mindspeed Technologies
illustrates the alternate lookup mechanism.
VCI [15:x]
shows the relationships of the values in VCI_IT_BLK_SZ, and the
Possible VCI Index
Table Entries per
Number of
VCC_BLOCK_INDEX
32,768
16,384
65,536
VCI Index Table
8,192
4,096
2,048
1,024
VPI
(For one VPI)
™
Where x = value of VCI_IT_BLK_SZ
Portion of Cell’s
(No pointer)
VCC Table
VCI[1:0]
VCI[2:0]
VCI[3:0]
VCI[4:0]
VCI[5:0]
5.2 Reassembly Functional Description
VCI[0]
is not applicable)
(For x=0, pointer
VCI
VCI [x-1:0]
5.0 Reassembly Coprocessor
Index Table Entry
Entries per VCI
Possible VCC
Reassembly
VCC Table
Number of
Section
16
32
64
1
2
4
8
5.7.1.
100074_025
5-5