Date   : Wed, 27 Jul 1994 08:55:28 WET DST
From   : Bonfield James <jkb@...>
Subject: Re: JB's macros!

Stephen Quan writes:

>And I was just wondering, (actually I had thought of this before),
>with C, you could use imbedded assebly.  Keep the macro as it is
>above, but you could have
>
>      #ifdef _386_
>      #define inc_PC(len) \
>        _asm add si,len
>      #endif
>
>      #ifdef _SPARC_
>      #define inc_PC(len) \
>        _asm add %o1,len,%o1
>      #endif

Is there a document available (preferably online) that describes how to use
asm? It always struck me as odd that you can do:

_asm add %o1,len,%o1.

This uses the first of the output registers (%o1) for the addition. How do we
know which register to use!? Isn't that the compilers task and not ours? Is
there a standard way of requesting PC to be register %o1? (There is in gcc -
just).

>#define Jmp(label)           _asm jmp @label
>#define Label(label)         _asm @label:
>#define Equw(label)          _asm @label

Is this @label notation part of the _asm semantics? Or is it architecture (and
maybe even 'as' (the UNIX assembler)) dependant?

If I could use assembly in the macros of my code it would enable, amongst
other things, the use of using the 386 status register as discussed in earlier
threads.

       James B