PowerPC inline assembler

The PowerPC 32bit instructionset is fully supported and complete.

For the simplified PowerPC mnemonics, resort to this module with preprocessing enabled: powerpc/simple.m

Up to 12 general purpose and 12 floating point registers may be used for register-variables.

Special addressing modes

There are no special instructions for accessing E variables.

To load a variable into register:

LWZ Rx, variable

To store a register into a variable:

STW Rx, variable

To get the address of a variable, use the “ADDI” instruction:

Translates to: ADDI Rx, localvar -> ADDI Rx, R1, localvar_offset ADDI Rx, globalvar -> ADDI Rx, R13, globalvar_offset

Local ARRAY/STRING/LIST “variables” are a bit different. They are not real variables but only represents the address of some storage on the stack.

To get the address of that data: ADDI Rx, local_array -> ADDI Rx, local_array_offset(R1)

Using a load or store instruction is still possible:

LWZ Rx, local_array -> LWZ Rx, local_array_offset(R1) -> this loads the first longword of the array into Rx.

For getting address of code labels, use the special “LA” instruction:

LA Rx, codelabel

We may dereference object members:

   LWZ Rx, .member(Ry:object)  -> LWZ Rx, member_offset(Ry)
   STB Rx .member(Ry:object)   -> STB Rx, member_offset(Ry)
   ADDI Rx, .member(Ry:object) -> ADDI Rx, Ry, member_offset
   STW Rx, .member(Ry:self)    -> STW Rx, member_offset(Ry) [in methods]

Registervariables (DEF :REG ...) may be used directly as if they were registers:

   DEF y:REG, x:REG PTR TO object
      LBZ y, .member(x)          -> LBZ Ry, member_offset(Rx)
      ADDI y, .member(x)         -> ADDI Ry, Rx, member_offset

Libraryfunction identifier may be used as constant (offset):

      ADDI R3, R0, AddTail        ..68K
      LWZ Rx, FindTaskByPID(Ry)   ..SYSV

Other special instructions:

Load Immediate Word

LIW Rx, <constant expression> -> May use two instructions if constant -> expression does not fit in 16bit.

Add Immediate Word

ADDIW Rx, <constant expression> -> May use two instructions if constant -> expression does not fit in 16bit.