AVR32AP datasheet(77/181 Pages) ATMEL

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32001A–AVR32–06/06

AVR32

as clean. If the write buffer is full the instruction will stall. If the line is not found or the line is

clean, nothing is done. If any MMU exceptions happen, the operation is silently aborted.

7.3.7

Clean & Invalidate

This operation performs a clean (as described in chapter 7.3.6) and then a invalidate (as

described in chapter 7.3.5).

7.4

Prefetch instruction

The prefetch operation will try to load the line containing the address given by the parameter into

the cache. If the line exists in the cache, nothing is done. If the line does not exist in the cache, it

will be fetched from the bus - even if the area is uncacheable. If any MMU exceptions happen,

the operation is silently aborted.

7.5

Sync instructions

The sync instruction will flush the write buffer, by forcing it to write any dirty data to the bus. This

can be used to ensure the data in main memory is consistent.

It will also ensure all pending read operations are completed, so e.g. invalidate and unlock oper-

ations are guaranteed to complete correctly.

7.6

Memory mapped cache memories

Both the data and tag memories of the DCache are mapped into the global address space, and

can be accessed by programs or through the SAP or OCD system. This can be used for com-

plex cache control, or simply as a very fast scratch RAM. The base address of the memory map

is IMPLEMENTATION DEFINED, but will always be in an unmapped privileged segment. The

size of the memory mapped area is always twice the cache size.

This mapped area is not available through the instruction cache or from peripherals, so it is not

possible to run programs from this area, or DMA data to or from it.

Note: Incorrect values written to the memory mapped cache memories may cause data corrup-

tion or unpredictable behaviour.

The DCache maps read or write requests to the cache memories by decoding the address as

shown below:

Figure 7-1.

DCache direct access addressing.

Base

T/D

Way

Set

Byte

AVR32AP Datasheet(PDF) 77 Page - ATMEL Corporation