5 memory-mapped cache associative write operation – Renesas SH7781 User Manual

Page 267

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8. Caches

Rev.1.00 Jan. 10, 2008 Page 237 of 1658

REJ09B0261-0100

Address field

31

23

5 4 3 2 1 0

1 1 1 1 0 1 0 1

Entry

Data field

31

0

Longword data

24

1312

14

15

L

*

: Longword specification bits
: Don't care

Way

0

L

0

* * * * * * * * *

Figure 8.8 Memory-Mapped OC Data Array (Cache size = 32 Kbytes)

8.6.5

Memory-Mapped Cache Associative Write Operation

Associative writing to the IC and OC address arrays may not be supported in future SuperH-
family products. The use of instructions ICBI, OCBI, OCBP, and OCBWB is recommended.
These instructions handle ITLB misses, and notify instruction TLB miss exceptions and data TLB
miss exceptions, thus providing a sure way of controlling the IC and OC. As a transitional
measure, this LSI generates address errors when this function is used. If compatibility with
previous products is a crucial consideration, on the other hand, the MMCAW bit in EXPMASK
(H'FF2F 0004) can be set to 1 to enable this function. However, instructions ICBI, OCBI, OCBP,
and OCBWB should be used to guarantee compatibility with future SuperH-family products.

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