B2.58
AArch32 Instruction Set Attribute Register 1, EL1
The ID_ISAR1_EL1 characteristics are:
Purpose
Provides information about the instruction sets implemented by the processor in AArch32.
Usage constraints
This register is accessible as follows:
EL0 EL1
(NS)
EL1
(S)
EL2 EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
RO
RO
RO
RO
RO
Configurations
ID_ISAR1_EL1 is architecturally mapped to AArch32 register ID_ISAR1. See
B1.75 Instruction Set Attribute Register 1
.
Attributes
ID_ISAR1_EL1 is a 32-bit register.
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 B2-31 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. This setting might indicate a trivial
implementation of the Jazelle extension.
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]
B2 AArch64 system registers
B2.58 AArch32 Instruction Set Attribute Register 1, EL1
100236_0100_00_en
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B2-457
Non-Confidential
Summary of Contents for Cortex-A35
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