System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-34
ID021414
Non-Confidential
Table 4-39
shows the ID_ISAR3_EL1 bit assignments.
To access the ID_ISAR3_EL1:
MRS <Xt>, ID_ISAR3_EL1 ; Read ID_ISAR3_EL1 into Xt
Register access is encoded as follows:
4.3.16
AArch32 Instruction Set Attribute Register 4
The ID_ISAR4_EL1 characteristics are:
Purpose
Provides information about the instruction sets implemented by the
processor in AArch32.
Table 4-39 ID_ISAR3_EL1 bit assignments
Bits
Name
Function
[31:28]
ThumbEE
Indicates the implemented Thumb Execution Environment (T32EE) instructions:
0x0
None implemented.
[27:24]
TrueNOP
Indicates support for True NOP instructions:
0x1
True
NOP
instructions in both the A32 and T32 instruction sets, and additional
NOP-compatible hints.
[23:20]
ThumbCopy
Indicates the support for T32 non flag-setting
MOV
instructions:
0x1
Support for T32 instruction set encoding T1 of the
MOV
(register) instruction, copying from
a low register to a low register.
[19:16]
TabBranch
Indicates the implemented Table Branch instructions in the T32 instruction set.
0x1
The
TBB
and
TBH
instructions.
[15:12]
SynchPrim
Indicates the implemented Synchronization Primitive instructions:
0x2
•
The
LDREX
and
STREX
instructions.
•
The
CLREX
,
LDREXB
,
STREXB
, and
STREXH
instructions.
•
The
LDREXD
and
STREXD
instructions.
[11:8]
SVC
Indicates the implemented SVC instructions:
0x1
The
SVC
instruction.
[7:4]
SIMD
Indicates the implemented
Single Instruction Multiple Data
(SIMD) instructions.
0x3
•
The
SSAT
and
USAT
instructions, and the Q bit in the PSRs.
•
The
PKHBT
,
PKHTB
,
QADD16
,
QADD8
,
QASX
,
QSUB16
,
QSUB8
,
QSAX
,
SADD16
,
SADD8
,
SASX
,
SEL
,
SHADD16
,
SHADD8
,
SHASX
,
SHSUB16
,
SHSUB8
,
SHSAX
,
SSAT16
,
SSUB16
,
SSUB8
,
SSAX
,
SXTAB16
,
SXTB16
,
UADD16
,
UADD8
,
UASX
,
UHADD16
,
UHADD8
,
UHASX
,
UHSUB16
,
UHSUB8
,
UHSAX
,
UQADD16
,
UQADD8
,
UQASX
,
UQSUB16
,
UQSUB8
,
UQSAX
,
USAD8
,
USADA8
,
USAT16
,
USUB16
,
USUB8
,
USAX
,
UXTAB16
,
UXTB16
instructions, and the GE[3:0] bits in the PSRs.
[3:0]
Saturate
Indicates the implemented Saturate instructions:
0x1
The
QADD
,
QDADD
,
QDSUB
,
QSUB
and the Q bit in the PSRs.
Table 4-40 ID_ISAR3_EL1 access encoding
op0
op1
CRn
CRm
op2
11
000
0000
0010
011