Filter
Top Products
System Control Coprocessor
ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 4-31
ID013010 Non-Confidential, Unrestricted Access
To access the Instruction Set Attributes Register 3 read CP15 with:
MRC p15, 0, <Rd>, c0, c2, 3 ; Read Instruction Set Attributes Register 3
c0, Instruction Set Attributes Register 4, ISAR4
The Instruction Set Attributes Register 4 provides information about the instruction set that the
processor supports beyond the basic set.
The Instruction Set Attributes Register 4 is:
• a read-only register
• accessible in Privileged mode only.
Figure 4-23 shows the bit arrangement for Instruction Set Attributes Register 4.
Figure 4-23 Instruction Set Attributes Register 4 format
Table 4-18 shows how the bit values correspond with the Instruction Set Attributes Register 4
functions.
[11:8] SVC instructions Indicates support for
SVC
(formerly
SWI
) instructions.
0x1
, the processor supports
SVC
.
[7:4] SIMD
instructions
Indicates support for Single Instruction Multiple Data (
SIMD
) instructions.
0x3
, the processor supports:
PKHBT
,
PKHTB
,
QADD16
,
QADD8
,
QASX
,
QSUB16
,
QSUB8
,
QSAX
,
SADD16
,
SADD8
,
SASX
,
SEL
,
SHADD16
,
SHADD8
,
SHASX
,
SHSUB16
,
SHSUB8
,
SHSAX
,
SSAT
,
SSAT16
,
SSUB16
,
SSUB8
,
SSAX
,
SXTAB16
,
SXTB16
,
UADD16
,
UADD8
,
UASX
,
UHADD16
,
UHADD8
,
UASX
,
UHSUB16
,
UHSUB8
,
USAX
,
UQADD16
,
UQADD8
,
UQASX
,
UQSUB16
,
UQSUB8
,
UQSAX
,
USAD8
,
USADA8
,
USAT
,
USAT16
,
USUB16
,
USUB8
,
USAX
,
UXTAB16
,
UXTB16
,
and the GE[3:0] bits in the PSRs.
[3:0] Saturate
instructions
Indicates support for saturate instructions.
0x1
, the processor supports
QADD
,
QDADD
,
QDSUB
,
QSUB
and Q flag in PSRs.
Table 4-17 Instruction Set Attributes Register 3 bit functions (continued)
Bits Field Function
31 24 23 20 19 16 15 12 11 8 7 4 3 0
Exclusive instructions
Barrier instructions
SMC instructions
Write-back instructions
With shift instructions
Unprivileged instructions
Reserved
Table 4-18 Instruction Set Attributes Register 4 bit functions
Bits Field Function
[31:24] Reserved SBZ.
[23:20] Exclusive instructions Indicates support for Exclusive instructions.
0x0
, Only supports synchronization primitive instructions as indicated by bits
[15:12] in the ISAR3 register. See c0, Instruction Set Attributes Register 3, ISAR3
on page 4-30 for more information.
[19:16] Barrier instructions Indicates support for Barrier instructions.
0x1
, the processor supports
DMB
,
DSB
, and
ISB
instructions.