SH7751 Group, SH7751R Group
Section 4 Caches
R01UH0457EJ0301 Rev. 3.01
Page 113 of 1128
Sep 24, 2013
H'7C00 2000 to H'7C00 3FFF (8 KB): Corresponds to RAM area 2
H'7C00 4000 to H'7C00 5FFF (8 KB): Corresponds to RAM area 1
H'7C00 6000 to H'7C00 7FFF (8 KB): Corresponds to RAM area 2
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:
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A shadow of the RAM area occurs every 16 Kbytes up to H'7FFF FFFF.
4.3.7
OC Index Mode
Setting CCR.OIX to 1 enables OC indexing to be performed using bit [25] of the effective
address. This is called OC index mode. In normal mode, with CCR.OIX cleared to 0, OC indexing
is performed using bits [13:5] of the effective address. Using index mode allows the OC to be
handled as two areas by means of effective address bit [25], providing efficient use of the cache.
Note that in the SH7751R, RAM mode cannot be used when OC index mode is used.
4.3.8
Coherency between Cache and External Memory
Coherency between cache and external memory should be assured by software. In this LSI, the
following four new instructions are supported for cache operations. Details of these instructions
are given in the Programming Manual.
Invalidate instruction:
OCBI @Rn
Cache invalidation (no write-back)
Purge instruction:
OCBP @Rn
Cache invalidation (with write-back)
Write-back instruction:
OCBWB @Rn
Cache write-back
Allocate instruction:
MOVCA.L R0,@Rn
Cache allocation
4.3.9
Prefetch Operation
This LSI supports a prefetch instruction to reduce the cache fill penalty incurred as the result of a
cache miss. If it is known that a cache miss will result from a read or write operation, it is possible
to fill the cache with data beforehand by means of the prefetch instruction to prevent a cache miss
due to the read or write operation, and so improve software performance. If a prefetch instruction
is executed for data already held in the cache, or if the prefetch address results in a UTLB miss or
a protection violation, the result is no operation, and an exception is not generated. Details of the
prefetch instruction are given in the Programming Manual.
Prefetch instruction:
PREF @Rn
Содержание SH7751 Group
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Страница 388: ...Section 12 Timer Unit TMU SH7751 Group SH7751R Group Page 334 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 800: ...Section 17 Smart Card Interface SH7751 Group SH7751R Group Page 746 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
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Страница 876: ...Section 20 User Break Controller UBC SH7751 Group SH7751R Group Page 822 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1036: ...Section 22 PCI Controller PCIC SH7751 Group SH7751R Group Page 982 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
Страница 1152: ...Appendix C Mode Pin Settings SH7751 Group SH7751R Group Page 1098 of 1128 R01UH0457EJ0301 Rev 3 01 Sep 24 2013 ...
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