Rev. 1.50, 10/04, page 179 of 448
Address field
31 23 12 5 4 2 1 0
11110001 Entry L
Data field
31 0
Longword data
L
*
24 131415
: Longword specification bits
: Don't care
Way
00
*********
Figure 8.6 Memory-Mapped IC Data Array
8.6.3 OC Address Array
The OC address array is allocated to addresses H'F400 0000 to H'F4FF FFFF in the P4 area. An
address array access requires a 32-bit address field specification (when reading or writing) and a
32-bit data field specification. The way and entry to be accessed are specified in the address field,
and the write tag, U bit, and V bit are specified in the data field.
In the address field, bits [31:24] have the value H'F4 indicating the OC address array, and the way
is specified by bits [14:13] and the entry by bits [12:5]. The association bit (A bit) [3] in the
address field specifies whether or not association is performed when writing to the OC address
array. As only longword access is used, 0 should be specified for address field bits [1:0].
In the data field, the tag is indicated by bits [31:10], the U bit by bit [1], and the V bit by bit [0].
As the OC address array tag is 19 bits in length, data field bits [31:29] are not used in the case of a
write in which association is not performed. Data field bits [31:29] are used for the virtual address
specification only in the case of a write in which association is performed.
The following three kinds of operation can be used on the OC address array:
1. OC address array read
The tag, U bit, and V bit are read into the data field from the OC entry corresponding to the
way and entry set in the address field. In a read, associative operation is not performed
regardless of whether the association bit specified in the address field is 1 or 0.
2. OC address array write (non-associative)
The tag, U bit, and V bit specified in the data field are written to the OC entry corresponding to
the way and entry set in the address field. The A bit in the address field should be cleared to 0.
When a write is performed to a cache line for which the U bit and V bit are both 1, after write-
back of that cache line, the tag, U bit, and V bit specified in the data field are written.
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