[CDG5] Process Manager

[Jason Duerstock]

Man, you should've asked.  "Check the compiler flags" would've been the
first thing I thought of.

On Sat, Dec 29, 2018 at 9:51 PM Elliot Nunn <elliotnunn at fastmail.com> wrote:

> Like Max, I had a bit of a code-generation problem last night. Thought
> I'd share it for your entertainment.
>
> As a big part of getting a System build to work, I am recreating the
> makefiles for the Process Manager. The Process Mgr has a very novel
> runtime (it actually gets loaded from 'scod' resources by the Segment
> Loader). With not many clues around about how to build it, I decided
> that I should take a deep dive at this point and get it round-tripping.
> System 7.1 seems to be a good fit.
>
> For context, the build is currently producing about 1/2 to 2/3 of a
> System file, albeit of dubious quality.
>
> Here is the function in question.
>
>         /* CheckUnitTableEntry.  See if the UNITTABLE entry that this
> driver would occupy
>          * is acceptable.  For now, just checks whether entry is already
> in use.
>          */
>         OSErr
>         CheckUnitTableEntry(short resourceID)
>                 {
>                 register DCtlPtr        dCtlPtr;
>                 DCtlHandle                      dCtlHdl;
>                 OSErr                           result;
>
>                 result = noErr;
>                 dCtlHdl = (DCtlHandle) UNITTABLE[resourceID];
>                 if ( (dCtlHdl != nil) && ((dCtlPtr = *dCtlHdl) != nil) &&
> ((dCtlPtr->dCtlFlags & DOpened) != 0) )
>                         result = portInUse;
>
>                 return(result);
>                 }
>
> UNITTABLE is defined as (*(Handle **)(0x11C))
>
> The unit table access was compiling to "EXT.L D0; MOVE.L $11C,A0; MOVE.L
> $0(A0,D0.L*4),A3" when I wanted "EXT.L D0; MOVE.L $11C,A0; ASL #2,D0;
> MOVE.L $0(A0,D0.L),A3". I fought with this until 1 am, changing headers,
> types and compiler versions to no avail. I found that the same motif
> appears in two or three places in that segment, and the ASL persists up
> to System 7.1.2, after which it was refactored out of existence.
>
> This morning I was about to email the list for help, when in a testament
> to the "starting really hard at a problem" methodology, the answer came
> to me. "MOVE.L $0(A0,D0.L*4),A3" is a very fancy-looking addressing
> mode, I thought. It wouldn't work on a vanilla M68k... Oh! System 7.1
> *does* run on a 68000, because it supports the Plus and Classic. (I
> should know, because I grew up using it on a Classic.) The C compiler
> was being run with the -mc68020 argument because I copied the makefile
> from the ROM build. Now fixed!
> _______________________________________________
> cdg5 mailing list
> cdg5 at ucc.asn.au
> https://lists.ucc.gu.uwa.edu.au/mailman/listinfo/cdg5
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://lists.ucc.gu.uwa.edu.au/pipermail/cdg5/attachments/20181229/7fe012a0/attachment.htm