cynse70032 Cypress Semiconductor Corporation., cynse70032 Datasheet - Page 53

• Manufacturer Part Number: cynse70032
• Description: Network Search Engine
• Manufacturer: Cypress Semiconductor Corporation.

The 136-bit word K (presented on the DQ bus in cycles A and B of the command) is also stored in the even and odd comparand
registers specified by the Comparand Register Index in the command’s cycle B. In ×136 configurations, the even and odd
comparand register can subsequently be used by the Learn command in only one of the devices (the first non-full device). The
word K (presented on the DQ bus in cycles A and B of the command) is compared to each entry in the table, starting at location 0.
The first matching entry’s location address L is the winning address that is driven as part of the SRAM address on the SADR[21:0]
lines (see “SRAM Addressing” on page 98). The global winning device will drive the bus in a specific cycle. On global miss cycles,
the device with LRAM = 1 (the default driving device for the SRAM bus) and LDEV = 1 (the default driving device for SSF and
SSV signals) will be the default driver for such missed cycles.
Search hit will always be at an even address.
The Search command is a pipelined operation and executes a Search at half the rate of the CLK2X frequency for 136-bit searches
in ×136-configured tables. The latency of SADR, CE_L, ALE_L, WE_L, SSV, and SSF from the 136-bit Search command cycle
(two CLK2X cycles) is shown in Table 13-12.
Table 13-12. Search Latency from Instruction to SRAM Access Cycle
For one to eight devices in the table and TLSZ = 01, Search latency from command to SRAM access cycle is 5. In addition, SSV
and SSF shift further to the right for different values of HLAT, as specified in Table 13-13.
Table 13-13. Shift of SSF and SSV from SADR
Document #: 38-02042 Rev. *E
Number of Devices
1–31 (TLSZ = 10)
1–8 (TLSZ = 01)
1 (TLSZ = 00)
HLAT
000
001
010
100
101
011
110
111
Must be same in each of the eight
Will be same in each of the eight
Comparand Register (odd)
Comparand Register (even)
67
devices
Figure 13-30. ×136 Table with Eight Devices
Max Table Size
248K × 136 bits
devices
64K × 136 bits
8K × 136 bits
A
B
0
Location
address
131070
GMR
Note
L
0
2
4
6
K
. During 136-bit searches of 136-bit-configured tables, the
135
135
Number of CLK Cycles
(136-bit configuration)
Even
CFG = 01010101
A
0
1
2
3
4
5
6
7
Odd
Latency in CLK Cycles
B
0
0
(First matching entry)
4
5
6
CYNSE70032
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