152
MicroBlaze Processor Reference Guide
UG081 (v14.7)
Chapter 4:
MicroBlaze Application Binary Interface
Register Usage Conventions
The register usage convention for MicroBlaze is given in
Table 4-2:
Register Usage Conventions
Register
Type
Enforcement
Purpose
R0
Dedicated
HW
Value 0
R1
Dedicated
SW
Stack Pointer
R2
Dedicated
SW
Read-only small data area anchor
R3-R4
Volatile
SW
Return Values/Temporaries
R5-R10
Volatile
SW
Passing parameters/Temporaries
R11-R12
Volatile
SW
Temporaries
R13
Dedicated
SW
Read-write small data area anchor
R14
Dedicated
HW
Return address for Interrupt
R15
Dedicated
SW
Return address for Sub-routine
R16
Dedicated
HW
Return address for Trap (Debugger)
R17
Dedicated
HW/SW
Return address for Exceptions
HW if configured to support hardware exceptions,
else SW
R18
Dedicated
SW
Reserved for Assembler/Compiler Temporaries
Used for Service ID with attribute svc_table_handler
R19
Non-volatile
SW
Must be saved across function calls. Callee-save
R20
Dedicated
or
Non-volatile
SW
Reserved for storing a pointer to the Global Offset Table
(GOT) in Position Independent Code (PIC). Non-volatile
in non-PIC code. Must be saved across function calls.
Callee-save
R21-R31
Non-volatile
SW
Must be saved across function calls. Callee-save
RPC
Special
HW
Program counter
RMSR
Special
HW
Machine Status Register
REAR
Special
HW
Exception Address Register
RESR
Special
HW
Exception Status Register
RFSR
Special
HW
Floating Point Status Register
RBTR
Special
HW
Branch Target Register
REDR
Special
HW
Exception Data Register
RPID
Special
HW
Process Identifier Register
RZPR
Special
HW
Zone Protection Register
RTLBLO
Special
HW
Translation Look-Aside Buffer Low Register
RTLBHI
Special
HW
Translation Look-Aside Buffer High Register
RTLBX
Special
HW
Translation Look-Aside Buffer Index Register
RTLBSX
Special
HW
Translation Look-Aside Buffer Search Index
RPVR0-
RPVR12
Special
HW
Processor Version Register 0 through 12
Содержание MicroBlaze
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