Calling PPC Shared Libraries from PPC Code 

Of course you do not need a contextswitch for this. It is completely PPC
Native to call a PPC Shared Library function from PPC Code. Currently,
there are not many PPC Shared Libraries available. There is powerpc.library,
of course, which contains some important functions like Memory Allocation
functions for PPC Native programs. I recommend STRONGLY that you read the
Autodocs of the powerpc.library, when your program needs some exec- or
utility-style functionality (Taglists, lists and messageports are for example
available PPC Native, also memory-protection on PPC-Side).

Then there is rtgmaster.library PPC version. Well, it is not yet released
to the public, but it soon will be. Asides from these two libs, there is
no PPC Shared Library yet released, as far as i know. But hopefully soon
there will be more. Maybe even one day the OS functions of the Amiga !!!

To call a PPC function you have to do the following:

- XREF the symbol _PowerPCBase
- create a valid stackframe, like described in Coding Subroutines
- include powerpc_lib.i (which will also include ppcmacros.i)
- use CALLPOWERPC of powerpc_lib.i to call the function.

Note: At least on my version of StormPowerASM, which appearently was quite
an early version (I got it on the Computer '97 directly from H&P) there is
a bit a chaos as to the includes on the CD. Some ASM-includes are in
stormc:asm-include and some in stormc:asm-includes. I simply copied those
in stormc:asm-include to stormc:asm-includes.

Example (from the StormPowerASM Docs, after some include path fixes)

    incdir "stormc:asm-includes"
    include exec/memory.i
    include "stormc:asm-includes/LVOs/powerpc_lib.i"

    XREF    _PowerPCBase

    executable
    version 7

start
    prolog                          ;build stackframe
    li      r4,4096                 ;4096 bytes to allocated
    liw     r5,MEMF_PUBLIC!MEMF_CLEAR ;memory flags
    li      r6,0                    ;no alignment restrictions
    CALLPOWERPC     AllocVecPPC     ;allocated memory
    tstw    r3                      ;test result
    beq     .exit                   ;if 0 then error
    mr      r4,r3                   ;move to r4
    CALLPOWERPC     FreeVecPPC      ;free allocated memory
.exit
    epilog                          ;remove stackframe

Note: The command "version 7" simply ensures, that at least powerpc.library V7
will be tried to be opened. As you see, you do not have to open powerpc.library
manually, the system will do this for you. Other PPC Shared Libraries will be
opened manually, of course. As OpenLibrary() is a 68k function, you would do
this in the 68k Part of your code, of course (For example, if you want to use
rtgmaster.library PPC version...).