SH7261 datasheet(220/1348 Pages) RENESAS

220 / 1348 page

Section 8 Cache

Rev. 2.00 Sep. 07, 2007 Page 188 of 1312

REJ09B0320-0200

127

V U

LW0

LW1

LW2

LW3

127

LRU

23 (1 + 1 + 21) bits

128 (32

× 4) bits

6 bits

LW0 to LW3: Longword data 0 to 3

Entry 0

Entry 1

Entry 127

Tag address

Address array (ways 0 to 3)

Data array (ways 0 to 3)

Figure 8.1 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 is composed of

21 bits (address bits 31 to 11) used for comparison during cache searches. In this LSI, as values of

addresses in the cache valid space are from H'00000000 to H'1FFFFFFF (see section 9, Bus State

Controller (BSC)), 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 and in deep standby mode 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.

The tag address becomes undefined after deep standby.

(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.

The data array becomes undefined after deep standby.

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