B2.66
ID_ISAR1_EL1, AArch32 Instruction Set Attribute Register 1, EL1
The ID_ISAR1_EL1 provides information about the instruction sets implemented by the core in
AArch32.
Bit field descriptions
ID_ISAR1_EL1 is a 32-bit register, and is part of the Identification registers functional group.
This register is Read Only.
31
28 27
24 23
20 19
16 15
12 11
8 7
4 3
0
Jazelle
Interwork
Immediate
IfThen
Extend
Except_AR
Except
Endian
Figure B2-50 ID_ISAR1_EL1 bit assignments
Jazelle, [31:28]
Indicates the implemented Jazelle state instructions:
0x1
Adds the
BXJ
instruction, and the J bit in the PSR.
Interwork, [27:24]
Indicates the implemented Interworking instructions:
0x3
• The
BX
instruction, and the T bit in the PSR.
• The
BLX
instruction. The PC loads have
BX
-like behavior.
• Data-processing instructions in the A32 instruction set with the PC as the
destination and the S bit clear, have
BX
-like behavior.
Immediate, [23:20]
Indicates the implemented data-processing instructions with long immediates:
0x1
• The
MOVT
instruction.
• The
MOV
instruction encodings with zero-extended 16-bit immediates.
• The T32
ADD
and
SUB
instruction encodings with zero-extended 12-bit immediates,
and other
ADD
,
ADR
, and
SUB
encodings cross-referenced by the pseudocode for
those encodings.
IfThen, [19:16]
Indicates the implemented If-Then instructions in the T32 instruction set:
0x1
The
IT
instructions, and the IT bits in the PSRs.
Extend, [15:12]
Indicates the implemented Extend instructions:
0x2
• The
SXTB
,
SXTH
,
UXTB
, and
UXTH
instructions.
• The
SXTB16
,
SXTAB
,
SXTAB16
,
SXTAH
,
UXTB16
,
UXTAB
,
UXTAB16
, and
UXTAH
instructions.
Except_AR, [11:8]
Indicates the implemented A profile exception-handling instructions:
0x1
The
SRS
and
RFE
instructions, and the A profile forms of the
CPS
instruction.
Except, [7:4]
Indicates the implemented exception-handling instructions in the A32 instruction set:
B2 AArch64 system registers
B2.66 ID_ISAR1_EL1, AArch32 Instruction Set Attribute Register 1, EL1
100798_0300_00_en
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B2-235
Non-Confidential
Summary of Contents for Cortex-A76 Core
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