HD6417750 Datasheet, PDF (166/1039 Pages) Renesas Technology Corp – SuperH RISC engine

31
24 23
Address field _{1 1 1 1 0 0 0 1}
13 12
Entry
54 210
L
31
0
Data field
Longword data
L : Longword specification bits
: Reserved bits (0 write value, undefined read value)
Figure 4.9 Memory-Mapped IC Data Array
4.5.3 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 entry to be accessed is 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
entry is specified by bits [13:5]. CCR.OIX and CCR.ORA have no effect on this entry
specification. The address array bit [3] association bit (A bit) 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
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 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.
Rev. 6.0, 07/02, page 114 of 986