SH7672 datasheet(129/1292 Pages) RENESAS

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Section 4 Cache

Rev. 1.00 Nov. 14, 2007 Page 103 of 1262

REJ09B0437-0100

(3)

Address-Array Write (Associative Operation)

When writing with the associative bit (A bit) of the address field set to 1, the addresses in the four

ways for the entry specified by the address field are compared with the tag address that is specified

by the data field. Write the U bit (only for operand cache) and the V bit specified by the data field

to the entry of the way that has a hit. However, the tag address and LRU bits remain unchanged.

When there is no way that has a hit, nothing is written and there is no operation.

This function is used to invalidate a specific entry in the cache. When the U bit of the entry that

has had a hit is 1 in the operand cache, writing back should be performed. However, when 0 is

written to the V bit, 0 must also be written to the U bit of that entry.

4.4.2

Data Array

To access a data array, the 32-bit address field (for read/write accesses) and 32-bit data field (for

write accesses) must be specified. The address field specifies information for selecting the entry to

be accessed; the data field specifies the longword data to be written to the data array.

Specify the entry address for selecting the entry, the L bit indicating the longword position within

the (16-byte) line, and the W bit for selecting the way. In the L bit, B'00 is longword 0, B'01 is

longword 1, B'10 is longword 2, and B'11 is longword 3. In the W bit, B'00 is way 0, B'01 is way

1, B'10 is way 2, and B'11 is way 3. Since the access size of the data array is fixed at longword,

specify B'00 for bits 1 and 0 of the address.

For the address and data formats, see figure 4.4.

The following two operations are possible for the data array. Information in the address array is

not modified by this operation.

(1)

Data Array Read

The data specified by the L bit in the address is read from the entry address specified by the

address and the entry corresponding to the way.

(2)

Data Array Write

The longword data specified by the data is written to the position specified by the L bit in the

address from the entry address specified by the address and the entry corresponding to the way.

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