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INSTRUCTION SET
S3C2501X
3-64
3.19 THUMB INSTRUCTION SET FORMAT
The thumb instruction sets are 16-bit versions of ARM instruction sets (32-bit format). The ARM instructions are
reduced to 16-bit versions, Thumb instructions, at the cost of versatile functions of the ARM instruction sets. The
thumb instructions are decompressed to the ARM instructions by the Thumb decompressor inside the
ARM9TDMI core.
As the Thumb instructions are compressed ARM instructions, the Thumb instructions have the 16-bit format
instructions and have some restrictions. The restrictions by 16-bit format is fully notified for using the Thumb
instructions.
3.19.1 FORMAT SUMMARY
The THUMB instruction set formats are shown in the following figure.
Move Shifted register
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
1
1
1
0
L
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
0
0
L
1
0
R
1
1
0
1
0
SP
1
L
L
S
H
0
0
1
B
L
0
1
H
0
1
B
0
0
1
1
1
I
Op
Op
Op
Op
Op
L
0
S
1
Offset5
Rs
Rd
Rn/offset3
Rd
Rs
Rd
Offset8
Rs
Rd/Hd
Rd
H1 H2
Rs/Hs
Rd
Word8
Rd
Rb
Ro
Ro
Rb
Rd
Offset5
Rb
Rd
Rb
Rd
Offset5
Rd
Rd
Word8
Word8
SWord7
Rb
Cond
Rlist
Rlist
Softset8
Value8
Offset11
Offset
Add/subtract
Move/compare/add/
subtract immediate
ALU operations
Hi regiter operations
/branch exchange
PC-relative load
Load/store with register
offset
Load/store with immediate
offset
Load/store sign-extended
byte/halfword
Load/store halfword
SP-relative load/store
Load address
Add offset to stack pointer
Push/pop register
Multiple load/store
Conditional branch
Software interrupt
Unconditional branch
Long branch with link
15 14 13 12 11 10
9
8
7
6
5
4
2
3
1
0
15 14 13 12 11 10
9
8
7
6
5
4
2
3
1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Figure 3-29. THUMB Instruction Set Formats
Summary of Contents for S3C2501X
Page 18: ......
Page 275: ...MEMORY CONTROLLER S3C2501X 5 60 NOTES ...
Page 289: ...I2C CONTROLLER S3C2501X 6 14 NOTES ...
Page 373: ...GDMA CONTROLLER S3C2501X 9 24 NOTES ...
Page 435: ...I O PORTS S3C2501X 12 12 NOTES ...