PowerPC Registers
General Purpose Registers
R0 - R31 (General Purpose Registers)
Used for various purposes including arithmetic operations, data storage, and function arguments.
Example:
li r0, 5 ; Load immediate value 5 into R0 addi r1, r0, 3 ; Add 3 to R0 and store the result in R1
Special Purpose Registers
LR (Link Register)
Stores the return address for function calls.
Example:
bl function ; Branch with link to function, LR is set to return address bclr 20, 0 ; Branch to address in LR
CTR (Count Register)
Used for loop control and branching.
Example:
mtctr r3 ; Move the value in R3 to CTR bdnz loop ; Branch to loop if CTR is not zero and decrement CTR
XER (Fixed-Point Exception Register)
Contains flags for fixed-point arithmetic exceptions.
Example:
addo r0, r1, r2 ; Add R1 and R2 with overflow detection, update XER
Floating-Point Registers
F0 - F31 (Floating-Point Registers)
Used for floating-point operations.
Example:
lfs f0, 0(r3) ; Load single-precision floating-point value from memory into F0 fadds f1, f0, f2 ; Add F0 and F2, store the result in F1
Condition Register
CR (Condition Register)
Contains condition flags for branching and comparisons.
Example:
cmpw r0, r1 ; Compare R0 and R1, update CR beq equal ; Branch to equal if CR indicates equality
Program Counter
PC (Program Counter)
Points to the next instruction to be executed.
Example:
b label ; Branch to label, PC is updated to the address of label
These registers are essential for various operations in PowerPC assembly programming, providing the necessary functionality for arithmetic, data manipulation, control flow, and memory access.