SH7670 Datasheet, PDF (114/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 4 Cache
Address array (ways 0 to 3)
Data array (ways 0 to 3)
Entry 0 V U Tag address
Entry 1
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0 _LW0
1
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LW1
LW2
LW3
LRU
0
1
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Entry 127
23 (1 + 1 + 21) bits
127
128 (32 × 4) bits
LW0 to LW3: Longword data 0 to 3
127
6 bits
Figure 4.1 Operand Cache Structure
(1) Address Array
The V bit indicates whether the entry data is valid. When the V bit is 1, data is valid; when 0, data
is not valid.
The U bit (only for operand cache) indicates whether the entry has been written to in write-back
mode. When the U bit is 1, the entry has been written to; when 0, it has not.
The tag address holds the physical address used in the external memory access. It consists of 21
bits (address bits 31 to 11) used for comparison during cache searches. In this LSI, the addresses
of the cache-enabled space are H'00000000 to H'1FFFFFFF (see section 7, Bus State Controller
(BSC)), and therefore the upper three bits of the tag address are cleared to 0.
The V and U bits are initialized to 0 by a power-on reset but not initialized by a manual reset or in
software standby mode. The tag address is not initialized by a power-on reset or manual reset or in
software standby mode.
(2) Data Array
Holds a 16-byte instruction or data. Entries are registered in the cache in line units (16 bytes).
The data array is not initialized by a power-on reset or manual reset or in software standby mode.
Rev. 1.00 Nov. 14, 2007 Page 88 of 1262
REJ09B0437-0100