Pagemask Register (5); Pagemask Register - NEC VR4181 mPD30181 User Manual

64-/32-bit microprocessor hardware
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3.2.5 PageMask register (5)

The PageMask register is a read/write register used for reading from or writing to the TLB; it holds a comparison
mask that sets the page size for each TLB entry, as shown in Table 3-3. Five page sizes can be selected between 1
KB and 256 KB.
TLB read and write instructions use this register as either a source or a destination; Bits 18 to 11 that are targets
of comparison are masked during address translation.
The contents of the PageMask register are undefined after a reset so that it must be initialized by software.
31
MASK:
Page comparison mask, which determines the virtual page size for the corresponding entry.
0:
Reserved for future use. Write 0 in a write operation. When this field is read, 0 is read.
Table 3-3 lists the mask pattern for each page size. If the mask pattern is one not listed below, the TLB behaves
unexpectedly.
Page size
1 KB
4 KB
16 KB
64 KB
256 KB
72
CHAPTER 3 CP0 REGISTERS
Figure 3-5. PageMask Register
19 18
0
MASK
Table 3-3. Mask Values and Page Sizes
18
17
16
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
User's Manual U14272EJ3V0UM
11 10
0
Bit
15
14
13
12
0
0
0
0
0
0
0
1
0
1
1
1
1
1
1
1
1
1
1
1
0
11
0
1
1
1
1

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