Jazelle DBX registers
ARM DDI 0388I
Copyright © 2008-2012 ARM. All rights reserved.
5-6
ID073015
Non-Confidential
To access the JOSCR, read or write the CP14 register with:
MRC p14, 7, <Rd>, c1, c0, 0; Read JOSCR
MCR p14, 7, <Rd>, c1, c0, 0; Write JOSCR
5.3.3
Jazelle Main Configuration Register
The JMCR characteristics are:
Purpose
Describes the Jazelle hardware configuration and its behavior.
Usage constraints
Only accessible in privileged modes.
Configurations
Available in all configurations.
Attributes
See the register summary in
.
shows the JMCR bit assignments.
Figure 5-3 JMCR bit assignments
shows the JMCR bit assignments.
31 30 29 28 27 26 25
1 0
nAR
FP
AP
OP
IS
SP
JE
UNK/SBZP
Table 5-4 JMCR bit assignments
Bits
Name
Function
[31]
nAR
not Array Operations
(nAR) bit.
0
Execute array operations in hardware, if implemented. Otherwise, call the appropriate handlers in
the VM Implementation Table.
1
Execute all array operations by calling the appropriate handlers in the VM Implementation Table.
[30]
FP
The FP bit controls how the Jazelle hardware executes JVM floating-point opcodes:
0
Execute all JVM floating-point opcodes by calling the appropriate handlers in the VM
Implementation Table.
1
Execute JVM floating-point opcodes by issuing
VFP
instructions, where possible.
Otherwise, call the appropriate handlers in the VM Implementation Table.
In this implementation FP is set to zero and is read-only.
[29]
AP
The
Array Pointer
(AP) bit controls how the Jazelle hardware treats array references on the operand stack:
0
Array references are treated as handles.
1
Array references are treated as pointers.
[28]
OP
The
Object Pointer
(OP) bit controls how the Jazelle hardware treats object references on the operand stack:
0
Object references are treated as handles.
1
Object references are treated as pointers.