Dear Jerry,
in message EGEGIJHKDKJGAJMGIDPNCEHJCCAA.jwalden@digitalatlantic.com you wrote:
Thanks for the clarification!
You are welcome.
I am used to the x86 world, and when I disassemble something, I am used to seeing a one for one mapping from instruction to op-code.
This is the same with PowerPC. But there may be several equivalent mnemonics to encode the same instruction. The green book ("The Programming Environments") says: "To simplify assembly language programming, a set of simplified mnemonics (referred to as extended mnemonics in the architecture specification) and symbols is provided ..."
It is obvious that I need to become more proficient in PPC assembly, how could you tell that the instruction we "equivalent" - did you use a tool, or is it that you are simply that familiar with the PPC assembly code.
In this case I didn't need a book; but you can actually look it up. For example your first statement:
addi r4,r0,0x0000
The green book lists for "addi":
addi rD,rA,SIMM
and the simplified mnemonics:
li rD,value equivalent to addi rD,0,value la rD,disp(rA) equivalent to addi rD,rA,disp subi rD,rA,value equivalent to addi rD,rA,-value
The listing you got from the disassembler:
fff80100: 38 80 00 00 li r4,0
obviously matches rule 1 (well, it's only obvious if you now about the special role or R0 in such cases :-).
Best regards,
Wolfgang Denk