System Control Coprocessor

c0, Instruction Set Attributes Register 3, ISAR3

The Instruction Set Attributes Register 3 provides information about the instruction set that the processor supports beyond the basic set.

The Instruction Set Attributes Register 3 is:

a read-only registers

accessible in Privileged mode only.

Figure 4-22shows the bit arrangement for Instruction Set Attributes Register 3.

31

28 27

24 23

20 19

16 15

12 11

8

7

4

3

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ThumbEE extension

True NOP instructions

Thumb copy instructions

Table branch instructions

Synchronization primitive instructions

SVC instructions

SIMD instructions

Saturate instructions

Figure 4-22 Instruction Set Attributes Register 3 format

Table 4-17shows how the bit values correspond with the Instruction Set Attributes Register 3 functions.

 

 

 

Table 4-17 Instruction Set Attributes Register 3 bit functions

 

 

 

Bits

Field

Function

 

 

 

[31:28]

ThumbEE

Indicates support for ThumbEE Execution Environment extension.

 

extension

0x0, no support.

 

 

 

[27:24]

True NOP

Indicates support for true NOP instructions.

 

instructions

0x1, the processor supports NOP16, NOP32 and various NOP compatible hints in both the ARM

 

 

and Thumb instruction sets.

 

 

 

[23:20]

Thumb copy

Indicates support for Thumb copy instructions.

 

instructions

0x1, the processor supports Thumb MOV(3) low register ⇒ low register.

 

 

 

[19:16]

Table branch

Indicates support for table branch instructions.

 

instructions

0x1, the processor supports table branch instructions, TBB and TBH.

 

 

 

[15:12]

Synchronization

Indicates support for synchronization primitive instructions.

 

primitive

0x2, the processor supports:

 

instructions

LDREX and STREX

 

 

 

 

LDREXB, LDREXH, LDREXD, STREXB, STREXH, STREXD, and CLREX.

ARM DDI 0363E

Copyright © 2009 ARM Limited. All rights reserved.

4-30

ID013010

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ARM R4F, r1p3 manual C0, Instruction Set Attributes Register 3, ISAR3, Instruction Set Attributes Register 3 bit functions