SH7261 datasheet(233/1348 Pages) RENESAS

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Section 8 Cache

Rev. 2.00 Sep. 07, 2007 Page 201 of 1312

REJ09B0320-0200

(2)

Address-Array Write (Non-Associative Operation)

When the associative bit (A bit) in the address field is cleared to 0, write the tag address, LRU bits,

U bit (only for operand cache), and V bit, specified by the data field, to the entry address specified

by the address and the entry corresponding to the way. When writing to a cache line for which the

U bit = 1 and the V bit =1 in the operand cache address array, write the contents of the cache line

back to memory, then write the tag address, LRU bits, U bit, and V bit specified by the data field.

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

(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.

8.4.2

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 8.4.

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

not modified by this operation.

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