ARM Cortex R4F - Manual (Page 112)

System Control Coprocessor
ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. 4-28
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Table 4-15 shows how the bit values correspond with the Instruction Set Attributes Register 1
functions.
To access the Instruction Set Attributes Register 1 read CP15 with:
MRC p15, 0, <Rd>, c0, c2, 1 ; Read Instruction Set Attributes Register 1
c0, Instruction Set Attributes Register 2, ISAR2
The Instruction Set Attributes Register 2 provides information about the instruction set that the
processor supports beyond the basic set.
The Instruction Set Attributes Register 2 is:
•
a read-only register
• accessible in Privileged mode only.
Table 4-15 Instruction Set Attributes Register 1 bit functions
Bits Field Function
[31:28] Jazelle
instructions Indicates support for Jazelle instructions.
0x1 , the processor supports:
• BXJ instruction
• J bit in PSRs.
For more information see Program status registers on page 2-10 and Acceleration of
execution environments on page 2-27.
[27:24] Interworking
instructions Indicates support for interworking instructions.
0x3 , the processor supports:
• BX , and T bit in PSRs
•
BLX
, and PC loads have BX behavior.
• Data-processing instructions in the ARM instruction set with the PC as the destination
and the S bit clear have BX-like behavior.
[23:20] Immediate
instructions Indicates support for immediate instructions.
0x1 , the processor supports:
• the MOVT instruction
• MOV instruction encodings with 16-bit immediates
• Thumb ADD and SUB instructions with 12-bit immediates.
[19:16] ITE
instructions Indicates support for if then instructions.
0x1
, the processor supports
IT
instructions.
[15:12] Extend
instructions Indicates support for sign or zero extend instructions.
0x2 , the processor supports:
•
SXTB
,
SXTB16
,
SXTH
,
UXTB
,
UXTB16
, and
UXTH
• SXTAB , SXTAB16 , SXTAH , UXTAB , UXTAB16 , and UXTAH .
[11:8] Exception 2
instructions Indicates support for exception 2 instructions.
0x1 , the processor supports RFE , SRS , and CPS .
[7:4] Exception 1
instructions Indicates support for exception 1 instructions.
0x1
, the processor supports
LDM
(exception return),
LDM
(user registers), and
STM
(user
registers).
[3:0] Endian
instructions Indicates support for endianness control instructions.
0x1
, the processor supports
SETEND
and E bit in PSRs.