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•
The alias word at 0x23FF.FFE0 maps to bit 0 of the bit-band byte at 0x200F.FFFF:0x23FF.FFE0 =
0x2200.0000 + (0x000F.FFFF*32) + (0*4)
•
The alias word at 0x23FF.FFFC maps to bit 7 of the bit-band byte at 0x200F.FFFF:0x23FF.FFFC =
0x2200.0000 + (0x000F.FFFF*32) + (7*4)
•
The alias word at 0x2200.0000 maps to bit 0 of the bit-band byte at 0x2000.0000:0x2200.0000 =
0x2200.0000 + (0*32) + (0*4)
•
The alias word at 0x2200.001C maps to bit 7 of the bit-band byte at 0x2000.0000:0x2200.001C =
0x2200.0000+ (0*32) + (7*4)
0x23FF.FFFC
0x2200.001C
7
6
5
4
0x200F.FFFF
7
6
5
4
0x2000.0003
24.6.4.1 Directly Accessing an Alias Region
Writing to a word in the alias region updates a single bit in the bit-band region.
Bit 0 of the value written to a word in the alias region determines the value written to the targeted bit in the
bit-band region. Writing a value with bit 0 set writes a 1 to the bit-band bit, and writing a value with bit 0
clear writes a 0 to the bit-band bit.
Bits 31:1 of the alias word have no effect on the bit-band bit. Writing 0x01 has the same effect as writing
0xFF. Writing 0x00 has the same effect as writing 0x0E.
When reading a word in the alias region, 0x0000.0000 indicates that the targeted bit in the bit-band region
is clear and 0x0000.0001 indicates that the targeted bit in the bit-band region is set.
24.6.4.2 Directly Accessing a Bit-Band Region
Section 24.6.2
describes the behavior of direct byte, halfword, or word accesses to the bit-band regions.
24.6.5 Data Storage
The processor views memory as a linear collection of bytes numbered in ascending order from zero. For
example, bytes 0-3 hold the first stored word, and bytes 4-7 hold the second stored word. Data is stored in
little-endian format, with the least-significant byte (lsbyte) of a word stored at the lowest-numbered byte,
and the most-significant byte (msbyte) stored at the highest-numbered byte.
data is stored.
SPRUHE8E – October 2012 – Revised November 2019
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Figure 24-12. Bit-Band Mapping
32-MB AliasRegion
0x23FF.FFF8
0x23FF.FFF4
0x23FF.FFF0
0x2200.0018
0x2200.0014
0x2200.0010
1-MB SRAMBit-BandRegion
3
2
1
0
7
6
5
4
3
2
0x200F.FFFE
3
2
1
0
7
6
5
4
3
2
0x2000.0002
Copyright © 2012–2019, Texas Instruments Incorporated
0x23FF.FFEC
0x23FF.FFE8
0x2200.000C
0x2200.0008
1
0
7
6
5
4
3
2
1
0
0x200F.FFFD
1
0
7
6
5
4
3
2
1
0
0x2000.0001
Memory Regions, Types and Attributes
0x23FF.FFE4
0x23FF.FFE0
0x2200.0004
0x2200.0000
7
6
5
4
3
2
1
0
0x200F.FFFC
7
6
5
4
3
2
1
0
0x2000.0000
Figure 24-13
illustrates how
Cortex-M3 Processor
1619
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