Oc Data Array; Figure 4.14 Memory-Mapped Oc Address Array - Hitachi SH7750 Hardware Manual

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.
3. OC address array write (associative)
When a write is performed with the A bit in the address field set to 1, the tag for each of the
ways stored in the entry specified in the address field is compared with the tag specified in the
data field. The way number set by bit [14] is not used. If the MMU is enabled at this time,
comparison is performed after the virtual address specified by data field bits [31:10] has been
translated to a physical address using the UTLB. If the addresses match and the V bit for that
way is 1, the U bit and V bit specified in the data field are written into the OC entry. This
operation is used to invalidate a specific OC entry. In other cases, no operation is performed. If
the OC entry U bit is 1, and 0 is written to the V bit or to the U bit, write-back is performed. If
an UTLB miss occurs during address translation, or the comparison shows a mismatch, an
exception is not generated, no operation is performed, and the write is not executed. If a data
TLB multiple hit exception occurs during address translation, processing switches to the data
TLB multiple hit exception handling routine.
31
Address field
1 1 1 1 0 1 0 0
31
Data field
V : Validity bit
U : Dirty bit
A : Association bit
: Reserved bits (0 write value, undefined read value)
4.6.4

OC Data Array

The OC data array is allocated to addresses H'F500 0000 to H'F5FF FFFF in the P4 area. A data
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 is specified in the address field, and the
longword data to be written is specified in the data field.
In the address field, bits [31:24] have the value H'F5 indicating the OC data array, the way is
specified by bit [14], and the entry by bits [13:5]. CCR.OIX has no effect on this entry
specification. In RAM mode (CCR.ORA = 1), the OC's data arrays are only accessible in the
memory-mapped cache area, and bit [13] is used to specify the way. For details about address
mapping, see section 4.6.5. Address field bits [4:2] are used for the longword data specification in
the entry. As only longword access is used, 0 should be specified for address field bits [1:0].
Rev. 6.0, 07/02, page 120 of 986
24 23
Tag

Figure 4.14 Memory-Mapped OC Address Array

15 14 13
Entry
Way
10 9
5 4 3 2 1 0
A
2 1 0
U V