System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-173
ID021414
Non-Confidential
Table 4-168
shows the ID_ISAR0 bit assignments.
To access the ID_ISAR0:
MRC p15, 0, <Rt>, c0, c2, 0 ; Read ID_ISAR0 into Rt
Register access is encoded as follows:
4.5.15
Instruction Set Attribute Register 1
The ID_ISAR1 characteristics are:
Purpose
Provides information about the instruction sets implemented by the
processor in AArch32.
Usage constraints
This register is accessible as follows:
Table 4-168 ID_ISAR0 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.
Table 4-169 ID_ISAR0 access encoding
coproc
opc1
CRn
CRm
opc2
1111
000
0000
0010
000
EL0
(NS)
EL0
(S)
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
RO
RO
RO
RO
RO