cynse70032 Cypress Semiconductor Corporation., cynse70032 Datasheet - Page 68

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

A logical 136-bit Search operation is shown in Figure 13-44. The entire table made up of 31 devices and consisting of 136-bit
entries is compared against a 136-bit word K that is presented on the DQ bus (using the GMR and local mask bits) in cycles A
and B of the command. The GMR is the 136-bit word specified by the even and odd global mask pair selected by the GMR Index
in the command’s cycle A.
The 136-bit word K that is 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 registers can subsequently be used by the Learn command in the first non-full device only.
command is supported for only one of the blocks consisting of up to eight devices in a depth-cascaded table of more than one
block. The word K that is presented on the DQ bus in cycles A and B of the command is compared with 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 Section 15.0, “SRAM Addressing” on page 98). The global winning device will drive the
bus in a specific cycle. In 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.
searches of 136-bit-configured tables, the Search hit will always be at an even address.
The Search command is a pipelined operation. It executes a Search at half the rate of the frequency of CLK2X 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 13-15.
Table 13-15. Search Latency from Instruction to SRAM Access Cycle
Search latency from command to SRAM access cycle is 6 for 1–31 devices in the table and TLSZ = 10. In addition, SSV and
SSF shift further to the right for different values of HLAT, as specified in Table 13-16.
Table 13-16. Shift of SSF and SSV from SADR
Document #: 38-02042 Rev. *E
entry and the hit flag (see page 14 for the description of SSR[0:7]). The DQ[67:0] is driven with 68-bit data ([67:0])to be compared
against all odd locations.
Number of Devices
1–31 (TLSZ = 10)
1–8 (TLSZ = 01)
1 (TLSZ = 00)
HLAT
Must be same in each of the 31
000
001
010
011
100
101
110
111
Will be same in each of the 31
Comparand Register (odd)
Comparand Register (even)
67
devices
devices
A
B
Max Table Size
248K × 136 bits
64K × 136 bits
Figure 13-44. x136 Table with 31 Devices
8K × 136 bits
0
507902
Location
address
GMR
L
0
2
4
6
K
135
135
(136-bit configuration)
Even
CFG = 01010101
A
Number of CLK Cycles
Odd
B
0
1
2
3
4
5
6
7
0
0
Latency in CLK Cycles
(First matching entry)
4
5
6
CYNSE70032
Note
Note
. During 136-bit
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. The Learn