AT697E datasheet(29/154 Pages) ATMEL

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AT697E

4226G–AERO–05/09

Diagnostic Cache

Access

Tags and data in the instruction and data cache can be accessed through ASI address

space 0xC, 0xD, 0xE and 0xF by executing LDA and STA instructions. Address bits

making up the cache offset will be used to index the tag to be accessed while the least

significant bits of the bits making up the address tag will be used to index the cache set.

Diagnostic read of tags is possible by executing an LDA instruction with ASI=0xC for

instruction cache tags and ASI=0xE for data cache tags. The cache line and the cache

set are indexed by the address bits making up the cache offset and the least significant

bits of the address bits making up the address tag.

Similarly, the data sub-blocks may be read by executing an LDA instruction with

ASI=0xD for instruction cache data and ASI=0xF for data cache data. The sub-block to

be read in the indexed cache line and set is selected by A[4:2].

The tags can be directly written by executing a STA instruction with ASI=0xC for the

instruction cache tags and ASI=0xE for the data cache tags. The cache line and cache

set are indexed by the address bits making up the cache offset and the least significant

bits of the address bits making up the address tag.

D[31:10] is written into the ATAG filed and the valid bits are written with the D[7:0] of the

write data. The data sub-blocks can be directly written by executing a STA instruction

with ASI=0xD for the instruction cache data and ASI=0xF for the data cache data. The

sub-block to be read in the indexed cache line and set is selected by A[4:2].

Note:

Diagnostic access to the cache is not possible during a FLUSH operation and will cause

a data exception (trap=0x09) if attempted.

AT697E Datasheet(PDF) 29 Page - ATMEL Corporation