Porting JWasm to ELKS using OpenWatcom C

[ghaerr]

@rafael2k writes (from #1443 (comment)):

In the meantime I tried to compile a full feature assembler, and managed to compile all files of JWasm (created a fork here: https://github.com/rafael2k/emasm ), just got some linking errors:

wmake -f OWELKS.mak
(...)
Error! E2028: alloca_ is an undefined reference
Error! E2028: strupr_ is an undefined reference
Error! E2028: remove_ is an undefined reference
Error! E2028: clock_ is an undefined reference
Error! E2028: __U8RS is an undefined reference
Error! E2028: _U8LS is an undefined reference
Error! E2028: ftruncate is an undefined reference
Error! E2028: __PIA is an undefined reference
Next for me is understand the owc build system to "remove" wlink and wasm from the owc build system.

[ghaerr]

The reasons for the undefined references and what needs to be done are as follows:

Error! E2028: remove_ is an undefined reference

remove is a system call that needs a wrapper written for ELKS, which will be similar to libc/watcom/syscall/rename.c.

Error! E2028: ftruncate is an undefined reference

ftruncate is a system call that is not implemented on ELKS. As such, some code within JWasm may need to be (re)written to truncate a file using creat possibly during the open. Further details after evaluating what's happening in JWasm.

Error! E2028: strupr_ is an undefined reference

We'll need to find a strupr implementation and add it to libc/string/strupr.c.

Error! E2028: __U8RS is an undefined reference
Error! E2028: _U8LS is an undefined reference
Error! E2028: __PIA is an undefined reference

These are OW library routines called from the OWC code generator. We'll need to pull them from the OWC source at bld/clib/cgsupp/a/pia.asm etc and copy them to libc/watcom/asm.

Error! E2028: alloca_ is an undefined reference

I'm pretty sure alloca is working with my OWC port. [EDIT: #include <alloca.h> will fix this].

Error! E2028: clock_ is an undefined reference

We'll need to read the OWC man page on its libc clock function, and implement that or call an ELKS libc equivalent.

All of this shouldn't a big deal, the question is how seriously you want to work get JWasm ported. I can help a lot and do some of the OW heavy lifting, but I'm not doing the actual port of JWasm. Let me know what you're thinking.

[ghaerr]

@rafael2k, I went ahead and added almost everything you should need for getting JWasm linked to #2104.

Reading the JWasm source, it seems ftruncate isn't needed anymore, change #define TRUNCATE 0 at the top of JWasm/omf.c.

Also, for now create a dummy clock() routine and add it to JWasm as follows. I haven't added a full version since I haven't been able to test it.

#include <time.h>

clock_t clock(void)
{
    return 0;
}

Later, we can add a full version, something like this (untested):

#include <time.h>
#include <sys/time.h>
#include <sys/times.h>

clock_t times(struct tms *tp)
{
        struct timeval tv;

        if (gettimeofday(&tv, (void *)0) < 0)
                return -1;

        if (tp) {
                clock_t usecs = tv.tv_sec * 1000000LL + tv.tv_usec; // FIXME calculate CLK_TCKs not usecs

                /* return user and system same since ELKS doesn't implement*/
                tp->tms_utime = usecs;
                tp->tms_stime = usecs;
                tp->tms_cutime = usecs;
                tp->tms_cstime = usecs;
        }

        return tv.tv_sec;
}

clock_t clock(void)
{
    struct tms  buf;

    times( &buf );
    return buf.tms_utime * (CLOCKS_PER_SEC / CLK_TCK);
}

[rafael2k]

Thanks a lot @ghaerr! Today at night I'll see if I can get jwasm linked!
I've already fixed the clock and remove (although may be I wrongfully substituted remove with unlink).

[rafael2k]

Btw, I'm doing the port and it is very close to working. Next I'll just need some help / advice on what to use to link the object file in ELKS (or may be just add rudimentary support for ELKS binary directly in JWasm?)

[rafael2k]

Just tested it again, now I get:

Error! E2028: __PIA is an undefined reference
Error! E2028: alloca_ is an undefined reference
Error! E2028: __U8RS is an undefined reference
Error! E2028: __U8LS is an undefined reference

I'll investigate a bit further.
Btw, to build for elks, just:

wmake -f OWELKS.mak

[rafael2k]

Got alloca. I had to include malloc.h first to alloca.h.
Now just:

Error! E2028: __PIA is an undefined reference
Error! E2028: __U8RS is an undefined reference
Error! E2028: __U8LS is an undefined reference

Which header provides them?

[rafael2k]

Btw copying over parts of your commit, now I get:

file out.lib(/home/rafael2k/programs/devel/elks/libc/watcom/asm/pia.asm): undefined symbol __HShift

[rafael2k]

Btw, the linking line:

owcc -bos2 -s -Wl,option -Wl,start=_start -Wl,option -Wl,dosseg -Wl,option -Wl,nodefaultlibs -Wl,option -Wl,stack=0x1000 -Wl,option -Wl,heapsize=0x1000 -Wl,library -Wl,/home/rafael2k/programs/devel/elks/libc/libc.lib -o OWELKSR/apiemu.obj OWELKSR/assemble.obj OWELKSR/assume.obj OWELKSR/atofloat.obj OWELKSR/backptch.obj OWELKSR/bin.obj OWELKSR/branch.obj OWELKSR/cmdline.obj OWELKSR/codegen.obj OWELKSR/coff.obj OWELKSR/condasm.obj OWELKSR/context.obj OWELKSR/cpumodel.obj OWELKSR/data.obj OWELKSR/dbgcv.obj OWELKSR/directiv.obj OWELKSR/elf.obj OWELKSR/end.obj OWELKSR/equate.obj OWELKSR/errmsg.obj OWELKSR/expans.obj OWELKSR/expreval.obj OWELKSR/extern.obj OWELKSR/fastpass.obj OWELKSR/fixup.obj OWELKSR/fpfixup.obj OWELKSR/hll.obj OWELKSR/input.obj OWELKSR/invoke.obj OWELKSR/label.obj OWELKSR/linnum.obj OWELKSR/listing.obj OWELKSR/loop.obj OWELKSR/lqueue.obj OWELKSR/macro.obj OWELKSR/mangle.obj OWELKSR/memalloc.obj OWELKSR/msgtext.obj OWELKSR/omf.obj OWELKSR/omffixup.obj OWELKSR/omfint.obj OWELKSR/option.obj OWELKSR/parser.obj OWELKSR/posndir.obj OWELKSR/preproc.obj OWELKSR/proc.obj OWELKSR/queue.obj OWELKSR/reswords.obj OWELKSR/safeseh.obj OWELKSR/segment.obj OWELKSR/simsegm.obj OWELKSR/string.obj OWELKSR/symbols.obj OWELKSR/tbyte.obj OWELKSR/tokenize.obj OWELKSR/types.obj OWELKSR/main.obj out.lib

out.lib from the watcom/asm directory

[ghaerr]

undefined symbol __HShift

For now, add unsigned char _HShift; (single underbar, not double) to your JSasm source code somewhere, this should allow it to link. I'll produce a PR with the proper fix and you can remove this later.

[ghaerr]

Actually, a unsigned char _HShift = 12; is required. We'll see whether JWasm runs or not... it seems there is some tricky handling of "huge" pointers within OWC's runtime which may require their own version of malloc, which could get complicated.

[rafael2k]

Yay, it runs! I'll try with different source files to check stability.

[rafael2k]

And you were also right about some tricky memory stuff. I might switch to official ow wasm.

[ghaerr]

out.lib from the watcom/asm directory

This is already included in the ELKS libc/libc.lib library - make sure that is both compiled by OWC correctly and in your link line.

The ELKS Watcom libc.lib is compiled using cd libc; make -f watcom.mk after setting libc/watcom.model's MODEL=l (for large) to match your compilation. I can't tell from your posts what model you are compiling JWasm but the library model has to match. It defaults to large model, which I would recommend for your first pass at all this.

And you were also right about some tricky memory stuff.

There are lots of potential issues but you've probably only set -Wl,option -Wl,heapsize=0x1000 which is a 4k heap. Try -Wl,option -Wl,heapsize=0x8000 which is 32k and see what happens.

[rafael2k]

Compiled ELKS/OS2 binary:
emasm.tar.gz