System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-28
ID021414
Non-Confidential
4.3.12
AArch32 Instruction Set Attribute Register 0
The ID_ISAR0_EL1 characteristics are:
Purpose
Provides information about the instruction sets implemented by the
processor in AArch32.
Usage constraints
This register is accessible as follows:
Configurations
ID_ISAR0_EL1 is architecturally mapped to AArch32 register
ID_ISAR0. See
Instruction Set Attribute Register 0
on page 4-172
.
Attributes
ID_ISAR0_EL1 is a 32-bit register.
Figure 4-11
shows the ID_ISAR0_EL1 bit assignments.
Figure 4-11 ID_ISAR0_EL1 bit assignments
Table 4-33
shows the ID_ISAR0_EL1 bit assignments.
To access the ID_ISAR0_EL1:
EL0
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
RO
RO
RO
RO
RO
31
28 27
24 23
20 19
16 15
12 11
8 7
4 3
0
RES
0
Divide
Debug
Coproc
CmpBranch
Bitfield
BitCount
Swap
Table 4-33 ID_ISAR0_EL1 bit assignments
Bits
Name
Function
[31:28]
-
Reserved,
RES
0.
[27:24]
Divide
Indicates the implemented Divide instructions:
0x2
•
SDIV
and
UDIV
in the T32 instruction set.
•
SDIV
and
UDIV
in the A32 instruction set.
[23:20]
Debug
Indicates the implemented Debug instructions:
0x1
BKPT
.
[19:16]
Coproc
Indicates the implemented Coprocessor instructions:
0x0
None implemented, except for separately attributed by the architecture including CP15,
CP14, Advanced SIMD and Floating-point.
[15:12]
CmpBranch
Indicates the implemented combined Compare and Branch instructions in the T32 instruction set:
0x1
CBNZ
and
CBZ
.
[11:8]
Bitfield
Indicates the implemented bit field instructions:
0x1
BFC
,
BFI
,
SBFX
, and
UBFX
.
[7:4]
BitCount
Indicates the implemented Bit Counting instructions:
0x1
CLZ
.
[3:0]
Swap
Indicates the implemented Swap instructions in the A32 instruction set:
0x0
None implemented.