R8A20210BG データシートの表示（PDF） - Renesas Electronics
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R8A20210BG Datasheet PDF : 14 Pages
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R8A20211BG/R8A20210BG (MARIE_Blade)
5. Greedy Operation
MARIE_Blade offers the Greedy operation to write to the DQ array. In the Greedy operation, Block 0-7 (figure 2)
are defined as Mat A, and Block 8-15 are defined as Mat B. The Greedy writes to an entry in each Mat at a time
(total two entries). The DQ pin [17:0] carries an address for access, but its value [17] selecting either MAT A or
MAT B is ignored in this case.
6. Hierarchical Search
MARIE_Blade has two types of search: the DX test logic search and the DQ array search. The DX Test Logic
consists of 4-bit entry, and DQ array, 72-bit entry. MARIE_Blade searches the DX Test Logic (primary search) first,
and then searches only the DQ array having a hit address of primary search (secondary search). Therefore the
Hierarchical Search can reduce power consumption.
Each block in the DX Test Logic has a single kind of data. Note: MARIE_Blade is not partitioned by configuration
(72-bit/144-bit/288-bit/576-bit). If the user does not utilize the DX Test Logic search, MARIE_Blade searches the
entire DQ array.
Secondary Search
DX
DQ
HIT!
DQ Array
Block
MISS
DQ Array
Block
DQ Array
MISS
MISS
DQ Array
Block
The Secondary Search operates only in
the block with the Primary Search hit.
Block
Figure 3 Hierarchical Search
7. Global Mask Search Register
The Global Mask Search Register (GMSR) controls bits that participate in the secondary search. The GMSR mask
consists of the same bit width as that of corresponding CAM DQ, and it masks per bit. The GMSR is valid only
during the secondary search. Note that the operation of other registers is restricted during the parallel mode.
Please refer to another section for details.
Search Comparison Data
DQ
Global Mask
0
1
1
X
1
1
X
0
TCAM DQ Array
The GMSR bit width is the same as that of DQ.
1-bit GMSR masks 1-bit DQ search key.
Figure 4 Global Mask Search
Rev.1.00 Feb 21, 2005 page 4 of 14
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