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Cache Operations 4-15
ICU tag information is placed into the ICDBDR as shown:
If CCR0[CIS] = 0, the data is a word of ICU data from the addressed line, specified by EA
27:29
. If
CCR0[CWS] = 0, the data is from the A-way; otherwise; the data from the B-way.
If CCR0[CIS] = 1, the cache information is the cache tag. If CCR0[CWS] = 0, the tag is from the A-
way; otherwise, the tag is from the B-way.
Programming Note: The instruction pipeline does not wait for data from an icread instruction to
arrive before attempting to use the contents the ICDBDR. The following code sequence ensures
proper results:
icread r5,r6# read cache information
isync # ensure completion of icread
mficdbdr r7# move information to GPR
4.5.3 DCU Debugging
The dcread instruction provides a debugging tool for reading the data cache entries for the
congruence class specified by EA
18:26
, unless no cache array is present. The cache information is
read into a GPR.
If CCR0[CIS] = 0, the data is a word of DCU data from the addressed line, specified by EA
27:29
. If
EA
30:31
are not 00, an alignment exception occurs. If CCR0[CWS] = 0, the data is from the A-way;
otherwise; the data is from the B-way.
If CCR0[CIS] = 1, the cache information is the cache tag. If CCR0[CWS] = 0, the tag is from the A-
way; otherwise the tag is from the B-way.
0:21 TAG Cache Tag
22:26
Reserved
27 V Cache Line Valid
0 Not valid
1 Valid
28:30
Reserved
31 LRU Least Recently Used (LRU)
0 A-way LRU
1 B-way LRU