
Cache
5-12
Freescale Semiconductor
5.3.5.1
Read Miss
A processor read that misses in the cache requests the cache controller to generate a bus transaction. This
bus transaction reads the needed line from memory and supplies the required data to the processor core.
The line is placed in the cache in the valid state.
5.3.5.2
Write Miss
The cache controller manages processor writes that miss in the cache differently for write-through and
copyback regions. Write misses to copyback regions cause the cache line to be read from system memory,
as shown in
Figure 5-7. Write-Miss in Copyback Mode
The new cache line is then updated with write data and the M bit is set for the line, leaving it in modified
state. Write misses to write-through regions write directly to memory without loading the corresponding
cache line into the cache.
5.3.5.3
Read Hit
On a read hit, the cache provides the data to the processor core and the cache line state remains unchanged.
If the cache mode changes for a specific region of address space, lines in the cache corresponding to that
region that contain modified data are not pushed out to memory when a read hit occurs within that line.
First execute a CPUSHL instruction or set CACR[CINVA] before switching the cache mode.
Cache Line
System
V = 1
M = 0
1. Write character X to 0x0B generates a write miss. Write cannot take place to an invalid line.
Memory
V = 0
M = 0
0x0C
0x00
0x08
0x04
2. The cache line (characters A–P) is updated from system memory and line is marked Valid.
X
ABCD EFGH IJKL MNOP
3. After the cache line is filled, the write that initiated the write -miss (the character X) completes to 0x0B.
V = 1
M = 1
0x0C
0x00
0x08
0x04
0x0C
0x00
0x08
0x04
ABCD EXGH IJKL MNOP
ColdFire
processor
ColdFire
processor
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...