Vfp11 System Registers; Table 20-3 Vfp11 System Registers - ARM ARM1176JZF-S Technical Reference Manual

20.4

VFP11 system registers

Register
Floating-Point System ID Register, FPSID
Floating-Point Status and Control Register, FPSCR
Floating-Point Exception Register, FPEXC
Floating-Point Instruction Register, FPINST
Floating-Point Instruction Register 2, FPINST2
Media and VFP Feature Register 0, MVFR0
Media and VFP Feature Register 1, MVFR1
ARM DDI 0301H
ID012310
The VFPv2 architecture describes the following three system registers that must be present in a
VFP system:
• Floating-Point System ID Register, FPSID
• Floating-Point Status and Control Register, FPSCR
• Floating-Point Exception Register, FPEXC.
The VFP11 coprocessor provides sufficient information for processing all exceptional
conditions encountered by the hardware. In an exceptional situation, the hardware provides:
• the exceptional instruction
• the instruction that might have been issued to the VFP11 coprocessor before detection of
the exception
• exception status information:
— type of exception
— number of remaining short vector iterations after an exceptional iteration.
To support exceptional conditions, the VFP11 coprocessor provides two additional registers:
• Floating-Point Instruction Register, FPINST
• Floating-Point Instruction Register 2, FPINST2.
Also, the FPEXC register contains additional bits to support exceptional conditions.
These registers are designed to be used with the support code software available from ARM
Limited. As a result, this document does not fully specify exception handling in all cases.
The coprocessor also provides two feature registers:
• Media and VFP Feature Register 0 on page 20-19, MVFR0
• Media and VFP Feature Register 1 on page 20-20, MVFR1.
Table 20-3 lists the VFP11 system registers.
Use the FMRX instruction to transfer the contents of VFP11 registers to ARM11 registers and
the FMXR instruction to transfer the contents of ARM11 registers to VFP11 registers.
Copyright © 2004-2009 ARM Limited. All rights reserved.
Non-Confidential, Unrestricted Access

Table 20-3 VFP11 system registers

Access mode Access type
Any Read-only
Any Read/write
Privileged Read/write
Privileged Read/write
Privileged Read/write
Any Read-only
Any Read-only
VFP Programmer's Model
Reset state See
0x410120B3 page 20-13
0x00000000 page 20-14
page 20-16
0x00000000
page 20-18
0xEE000A00
UNP page 20-18
page 20-19
0x11111111
page 20-20
0x00000000
20-12