Figure 2-4. Bit-Band Mapping
0x23FF.FFE4
0x2200.0004
0x23FF.FFE0
0x23FF.FFE8
0x23FF.FFEC
0x23FF.FFF0
0x23FF.FFF4
0x23FF.FFF8
0x23FF.FFFC
0x2200.0000
0x2200.0014
0x2200.0018
0x2200.001C
0x2200.0008
0x2200.0010
0x2200.000C
32-MB Alias Region
0
7
0
0
7
0x2000.0000
0x2000.0001
0x2000.0002
0x2000.0003
6
5
4
3
2
1
0
7
6
5
4
3
2
1
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0x200F.FFFC
0x200F.FFFD
0x200F.FFFE
0x200F.FFFF
1-MB SRAM Bit-Band Region
2.4.5.1
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.
2.4.5.2
Directly Accessing a Bit-Band Region
“Behavior of Memory Accesses” on page 107 describes the behavior of direct byte, halfword, or word
accesses to the bit-band regions.
2.4.6
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.
Figure 2-5 on page 112 illustrates how data is stored.
111
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller
