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ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 4-30
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c0, Instruction Set Attributes Register 3, ISAR3
The Instruction Set Attributes Register 3 provides information about the instruction set that the
processor supports beyond the basic set.
The Instruction Set Attributes Register 3 is:
• a read-only registers
• accessible in Privileged mode only.
Figure 4-22 shows the bit arrangement for Instruction Set Attributes Register 3.
Figure 4-22 Instruction Set Attributes Register 3 format
Table 4-17 shows how the bit values correspond with the Instruction Set Attributes Register 3
functions.
31 28 27 24 23 20 19 16 15 12 11 8 7 4 3 0
ThumbEE extension
True NOP instructions
Thumb copy instructions
Table branch instructions
Synchronization primitive instructions
SVC instructions
SIMD instructions
Saturate instructions
Table 4-17 Instruction Set Attributes Register 3 bit functions
Bits Field Function
[31:28] ThumbEE
extension
Indicates support for ThumbEE Execution Environment extension.
0x0
, no support.
[27:24] True NOP
instructions
Indicates support for true
NOP
instructions.
0x1
, the processor supports
NOP16
,
NOP32
and various
NOP
compatible hints in both the ARM
and Thumb instruction sets.
[23:20] Thumb copy
instructions
Indicates support for Thumb copy instructions.
0x1
, the processor supports Thumb
MOV(3)
low register ⇒ low register.
[19:16] Table branch
instructions
Indicates support for table branch instructions.
0x1
, the processor supports table branch instructions,
TBB
and
TBH
.
[15:12] Synchronization
primitive
instructions
Indicates support for synchronization primitive instructions.
0x2
, the processor supports:
•
LDREX
and
STREX
•
LDREXB
,
LDREXH
,
LDREXD
,
STREXB
,
STREXH
,
STREXD
, and
CLREX
.