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 PLASMA virtual machine on the OPC6 
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
Here's an example to show what I'm talking about:
Code:
steven@riemann:~/src/PLASMA-opc6$ cat equexample.s
   ORG 0x0200
   UBYTE   0x00         # ZERO
   EQU _SYSFLAGS, 0
steven@riemann:~/src/PLASMA-opc6$ python opc6byteasm.py equexample.s
0400                          ORG 0x0200
0400 00                       UBYTE   0x00         # ZERO
0401                          EQU _SYSFLAGS, 0

Assembled 1 bytes of code with 2 errors and 0 warnings.

Symbol Table:

PC                               0x0200 (000512)
_BPC_                            0x0400 (001024)
_SYSFLAGS                        0x0000 (000000)

Error: found word label directive or instruction on unaligned byte ...
        EQU _SYSFLAGS, 0

Error: found word label directive or instruction on unaligned byte ...
        EQU _SYSFLAGS, 0

If I add an ALIGN before the EQU line it assembles fine. As I say, it isn't causing me any real problems, but I find this mildly counterintuitive, since that line as far as I know is just setting the variable (I perhaps shouldn't call it a label) _SYSFLAGS to 0 and doesn't use the current word position.


Thu Aug 10, 2017 9:29 pm
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Joined: Tue Apr 25, 2017 7:33 pm
Posts: 31
Aha. OK that is unexpected. Fixed now and the non-zero exit status on errors too.

R


Thu Aug 10, 2017 9:45 pm
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
Both changes work, thanks!


Thu Aug 10, 2017 9:48 pm
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
I've been implementing some more VM opcodes and I've been trying to use a modified version of Ed's cmpsigned() macro. I infer that the extra __ arguments to the macro are essentially a way of getting local labels; is that right?

I'm hitting problems with redefinition of those labels - apologies if I've introduced a bug, but here's a cut-down test case demonstrating my problem:
Code:
steven@riemann:~/src/opc/opc6$ cat error.s
   ORG 0x1000

MACRO zero(dest, __bar)
__bar:
   mov dest, r0
ENDMACRO

   zero(r1)
   zero(r2)
steven@riemann:~/src/opc/opc6$ python opc6byteasm.py error.s mem
2000                          ORG 0x1000
2000                       
2000                       # MACRO zero(dest, __bar)
2000                       # __bar:
2000                       #    mov dest, r0
2000                       # ENDMACRO
2000                       
2000                       #   zero(r1)
2000                       __bar:
2000 01 00                    mov r1, r0
2002                       #   zero(r2)
2002                       __bar:
2002 02 00                    mov r2, r0

Assembled 4 bytes of code with 1 error and 0 warnings.

Symbol Table:

PC                               0x1002 (004098)
_BPC_                            0x2002 (008194)
__bar                            0x1001 (004097)

Error: Symbol            __bar redefined in ...
         __bar:


Is this supposed to work, and if not is there some other way to get the effect of local labels in a macro?

Cheers.

Steve


Fri Aug 11, 2017 10:12 pm
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Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1284
I think revaldinho may have broken something recently! He added an '@' suffix to make this kind of thing a bit easier, but it's not quite right yet.

Edit: oops! That's not quite it. See below.


Sat Aug 12, 2017 7:50 am
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Joined: Tue Apr 25, 2017 7:33 pm
Posts: 31
Steve,

You're half way there.

You've defined the local label as a parameter in the macro definition...

Code:
MACRO zero( dest, __bar)


...but then not supplied a parameter value in the macro instances.

Code:
zero (r1)
zero (r2)


If you add unique tokens to your macro instances then this will work, ie

Code:
zero ( r1, L0001)
zero (r2,L0002)


This is the origninal 'free' local label implementation. As Ed says I am adding a better local labelling function where you don't need to track the labels yourself. This isn't working yet but it's not related to this issue. I have a testcase from Dave to look at but won't be at my computer 'til later today. It won't take long to fix so will probably push that change if not later today then early tomorrow.

R


Sat Aug 12, 2017 8:09 am
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Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1284
Oops! Thanks for the correction.


Sat Aug 12, 2017 8:14 am
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
Thanks, I've added some unique tokens to my macro instances and it works now. I'll change this when the enhancement is available but it's not a big deal either way.

Cheers.

Steve


Sat Aug 12, 2017 11:03 am
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Joined: Tue Apr 25, 2017 7:33 pm
Posts: 31
Just pushed a fix for Dave's testcase in both word and byte assemblers so the new local label scheme is working in the latest GitHub code.

No need to declare any parameters on macros or track labels yourself now. Just put the '@' symbol in any local label and it will get replaced with the macroname and a counter value each time it's used. Nested macros are still allowed.

Here's a simple example using a cut down version of Dave's testcase with the byte assembler

Code:
        EQU __divu, 0x1234
        EQU __modu, 0x5678

MACRO SW16 ( _sub_ )
      pl.inc  pc, l1_@ - PC
      inc     r5, 1
l1_@:
      add     r2, r0
      pl.inc  pc, l2_@ - PC
      jsr     r13,r0, _sub_
l2_@:
      mov     pc, r13
ENDMACRO       

__div:
     SW16(__divu)

__mod:
     SW16(__modu)


assembles into ...

Code:
0000                       
0000                               EQU __divu, 0x1234
0000                               EQU __modu, 0x5678
0000                       
0000                       # MACRO SW16 ( _sub_ )
0000                       #       pl.inc  pc, l1_@ - PC
0000                       #       inc     r5, 1
0000                       # l1_@:
0000                       #       add     r2, r0
0000                       #       pl.inc  pc, l2_@ - PC
0000                       #       jsr     r13,r0, _sub_
0000                       # l2_@:
0000                       #       mov     pc, r13
0000                       # ENDMACRO
0000                       
0000                       __div:
0000                       #     SW16(__divu)
0000 1f ec                       pl.inc  pc, l1_SW16_0 - PC
0002 15 0c                       inc     r5, 1
0004                       l1_SW16_0:
0004 02 04                       add     r2, r0
0006 2f ec                       pl.inc  pc, l2_SW16_0 - PC
0008 0d 19 34 12                 jsr     r13,r0, __divu
000c                       l2_SW16_0:
000c df 00                       mov     pc, r13
000e                       
000e                       __mod:
000e                       #     SW16(__modu)
000e 1f ec                       pl.inc  pc, l1_SW16_1 - PC
0010 15 0c                       inc     r5, 1
0012                       l1_SW16_1:
0012 02 04                       add     r2, r0
0014 2f ec                       pl.inc  pc, l2_SW16_1 - PC
0016 0d 19 78 56                 jsr     r13,r0, __modu
001a                       l2_SW16_1:
001a df 00                       mov     pc, r13
001c                       

Assembled 28 bytes of code with 0 errors and 0 warnings.

Symbol Table:

PC                               0x0000E (000014)
_BPC_                            0x0001A (000026)
__div                            0x00000 (000000)
__divu                           0x01234 (004660)
__mod                            0x00007 (000007)
__modu                           0x05678 (022136)
l1_SW16_0                        0x00002 (000002)
l1_SW16_1                        0x00009 (000009)
l2_SW16_0                        0x00006 (000006)
l2_SW16_1                        0x0000D (000013)


Sat Aug 12, 2017 5:58 pm
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
Thanks, I've updated my code to use that and it works!


Sat Aug 12, 2017 6:04 pm
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
I'm continuing to implement more of the VM opcodes and I now need to do the MUL, DIV and MOD opcodes, which carry out signed 16-bit multiplication, division and remainder.

I see there is a udiv16 and a mul16 in math16.s in the opc repository, so:
  • Is the author of that code (Revaldinho?) OK with me including it in the GPL3-licensed PLASMA repository?
  • Does anyone have any signed 16-bit division/remainder code? I can probably modify the udiv16 routine but I'm not all that comfortable implementing these kind of things and it would be nice if there's already some tested code I can re-use.

Cheers.

Steve


Sun Aug 13, 2017 7:25 pm
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Joined: Tue Feb 10, 2015 7:07 am
Posts: 50
Steve,

I've just pulled together such a set of routines for the C compiler:
https://github.com/hoglet67/opc/blob/c_ ... ot-c/lib.s

Dave


Sun Aug 13, 2017 8:02 pm
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
Thanks Dave, they look great - are you OK for me to include that code in my GPLv3-licensed repository?


Sun Aug 13, 2017 8:05 pm
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Joined: Tue Feb 10, 2015 7:07 am
Posts: 50
SteveF wrote:
Thanks Dave, they look great - are you OK for me to include that code in my GPLv3-licensed repository?

That's fine as far as I'm concerned.

Dave


Sun Aug 13, 2017 8:30 pm
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Joined: Sat Aug 05, 2017 6:57 pm
Posts: 26
Further progress... The PLASMA VM now starts up, displays the usual banner message and then dies because I haven't implemented the gets() function it uses to accept user input yet...
Code:
steven@riemann:~/src/PLASMA-opc6$ ./doit2.sh
[...]
steven@riemann:~/src/PLASMA-opc6$ ls -l emuout.txt
-rw-rw-r-- 1 steven steven 15693204 Aug 15 21:55 emuout.txt
steven@riemann:~/src/PLASMA-opc6$ python output.py emuout.txt
PLASMA 00.99
MEM FREE:$E1DC, AUX FREE:$FFF6

output.py is just grabbing OUT instructions from the emulator output and assuming they are all attempts to print ASCII characters.

I think there is a lurking issue around the handling of function addresses but this is actually probably 50-75% of the way to being a working port, if an inefficient one which is ripe for tuning. (But that's the really fun bit, right? :-) )

It might be worth pointing out here that a full PLASMA implementation is something that expects to have a filesystem from which it can load modules containing user code (and ideally a terminal to interact with the user on). It would certainly be possible to use the core PLASMA VM to build a standalone executable with a hard-coded PLASMA program (and that might be appropriate for an embedded use), and what I've implemented already more-or-less provides that. (Just use 'doit.sh myprog.pla' to compile and run, but note that as it stands the program has no access to any standard PLASMA functions - just the core language. Kind of like a freestanding C implementation, I guess.)

I can certainly make further progress towards a full implementation with the Python command line emulator, but at this point it would be very nice if I had a version of b-em with the PiTubeDirect OPC6 co-pro available.

Dave - I see you're busy with the C64 port and probably other stuff as well, would you be willing to have a go at creating such a version of b-em, please? If not I can have a go at it myself. I'm also quite happy to break off development of the OPC6 port temporarily if you're interested in doing this but not right now.

I have had a quick look at the OPC6 co-pro client ROM in the repository and I suspect I'd also have some further questions/requests for implementation of more OS calls/advice on how to extend the client ROM to do those myself. I'd really like to have the following (plus some which already seem to be supported):
  • OSFIND (open file for input/close file)
  • OSGBPB (read ignoring PTR#)
  • OSARGS (read extent)

Cheers.

Steve


Tue Aug 15, 2017 9:12 pm
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