
Section 7 Cache
Rev. 4.00 Sep. 14, 2005 Page 180 of 982
REJ09B0023-0400
7.1.1 Cache
Structure
The cache mixes data and instructions and uses a 4-way set associative system. It is composed of
four ways (banks), each of which is divided into an address section and a data section. Each of the
address and data sections is divided into 256 entries. The data section of the entry is called a line.
Each line consists of 16 bytes (4 bytes
×
4). The data capacity per way is 4 kbytes (16 bytes
×
256
entries), with a total of 16 kbytes in the cache as a whole (4 ways). Figure 7.1 shows the cache
structure.
24 (1 + 1 + 22) bits
128 (32
´
4) bits
6 bits
LW0 to LW3: Longword data 0 to 3
Entry 0
Entry 1
Entry 255
0
1
255
0
1
255
V
U
Tag address
LW0
LW1
LW2
LW3
Address array (ways 0 to 3)
Data array (ways 0 to 3)
LRU
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Figure 7.1 Cache Structure
Address Array: The V bit indicates whether the entry data is valid. When the V bit is 1, data is
valid; when 0, data is not valid. The U bit indicates whether the entry has been written to in write-
back mode. When the U bit is 1, the entry has been written to; when 0, it has not. The address tag
holds the physical address used in the external memory access. It is composed of 22 bits (address
bits 31 to 10) used for comparison during cache searches.
In this LSI, the top three of 32 physical address bits are used as shadow bits (see section 12, Bus
State Controller (BSC)), and therefore the top three bits of the tag address are cleared to 0.
The V and U bits are initialized to 0 by a power-on reset and retain the previous value by a manual
reset, standby mode, module standby mode, and sleep mode. The tag address is not initialized by a
power-on or manual reset, standby mode, module standby mode, and sleep mode.
Summary of Contents for HD6417641
Page 2: ...Rev 4 00 Sep 14 2005 Page ii of l...
Page 7: ...Rev 4 00 Sep 14 2005 Page vii of l...
Page 11: ...Rev 4 00 Sep 14 2005 Page xi of l USB Universal serial bus WDT Watch dog timer...
Page 12: ...Rev 4 00 Sep 14 2005 Page xii of l...
Page 28: ...Rev 4 00 Sep 14 2005 Page xxviii of l...
Page 204: ...Section 4 Clock Pulse Generator CPG Rev 4 00 Sep 14 2005 Page 154 of 982 REJ09B0023 0400...
Page 212: ...Section 5 Watchdog Timer WDT Rev 4 00 Sep 14 2005 Page 162 of 982 REJ09B0023 0400...
Page 228: ...Section 6 Power Down Modes Rev 4 00 Sep 14 2005 Page 178 of 982 REJ09B0023 0400...
Page 246: ...Section 8 X Y Memory Rev 4 00 Sep 14 2005 Page 196 of 982 REJ09B0023 0400...
Page 318: ...Section 11 User Break Controller UBC Rev 4 00 Sep 14 2005 Page 268 of 982 REJ09B0023 0400...
Page 454: ...Section 12 Bus State Controller BSC Rev 4 00 Sep 14 2005 Page 404 of 982 REJ09B0023 0400...
Page 504: ...Section 14 U Memory Rev 4 00 Sep 14 2005 Page 454 of 982 REJ09B0023 0400...
Page 566: ...Section 17 Compare Match Timer CMT Rev 4 00 Sep 14 2005 Page 516 of 982 REJ09B0023 0400...
Page 868: ...Section 21 A D Converter Rev 4 00 Sep 14 2005 Page 818 of 982 REJ09B0023 0400...
Page 914: ...Section 23 I O Ports Rev 4 00 Sep 14 2005 Page 864 of 982 REJ09B0023 0400...
Page 956: ...Section 24 List of Registers Rev 4 00 Sep 14 2005 Page 906 of 982 REJ09B0023 0400...
Page 1016: ...Section 25 Electrical Characteristics Rev 4 00 Sep 14 2005 Page 966 of 982 REJ09B0023 0400...
Page 1024: ...Appendix Rev 4 00 Sep 14 2005 Page 974 of 982 REJ09B0023 0400...
Page 1032: ...Rev 4 00 Sep 14 2005 Page 982 of 982 REJ09B0023 0400 X X Y data addressing 52 X Y memory 193...
Page 1035: ......
Page 1036: ...SH7641 Hardware Manual...