Register Usage

There are 16, 32-bit general purpose registers which can be used for both integer values and single-precision floating point values. There are also a set of control registers. The registers are shown in the following tables:
Register Name(s) Usage
r0
Stack pointer
r1
Scratch register
r2-r3
Parameter registers, return value
r4-r7
Parameter registers
r8-r13
Permanent registers
r14
Permanent register, frame pointer
r15
Link pointer

Registers r1-r7, r15 are volatile; their contents may be destroyed by a function call. Registers r0, r8-r14 are non-volatile; they will be preserved across function calls.
Name Usage
PSR
Processor status register
VBR
Vector base register
EPSR, FPSR, EPC, FPC
Exception shadow registers
SS0-SS4
Supervisor storage registers
GCR
Global control register
GSR
Global status register
PC
Program counter


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