Re: Unpack/Huffman coding in colorForth

Hi, Albert and friends,
Ray here.

On 4/10/05, Albert van der Horst <[email protected]> wrote:
> On Sun, Apr 10, 2005 at 01:49:55PM -0400, Mark Slicker wrote:
> <SNIP>
> >
> > The bootable colorForth images are mostly the same. Either Terry's or
> > Chuck's image is fine.
> 
> "
>         From: "howerd.oakford" <[email protected]>
>         I would be delighted if you would disassemble and re-assemble
>         the binary image cfdos4.blk ! ( blocks 0 to 17 )
>         Its available from my website www.inventio.co.uk/cfdos.htm .
> "
> Howard was so kind to supply me with the above url.
> 
> But I conclude from what you say that the version obtainable
> via
>         http://www.colorforth.com/install.htm
> is in fact stable and recent.
> So that is the proper starting point against which to report
> improvements and updates. It is probably the same as Howards
> anyway.
> 

On 4/21/05, Albert van der Horst <[email protected]> wrote:
> Hoy Folks,
> Have the Huffman codes changed in historic times?
> 
> I have had some success in automatically extracting names from a
> colorforth image, and use those names in the disassembly.
> But `` 1,  '' wants to be seen as `` z, '' and 2, as j, .
> 

I believe that Howerd has fixed many of the bugs that are in the
colorforth that you found in the image you extracted from Chuck\(Terry
too?) . His version is different, as Chuck\Terry\Ray-hacked-version
runs on my HP/Compaq P4, but Howerds doesn't. Howerds does run on my
P1, (when my p1 runs :) ).

So, I think you'll find some minor diffs between those versions.

This below is very very kewl.

> ---------------------------
> ( 0000,0645 )   :X_,    MOVI|X, CX| 4 IL,
> ( 0000,064A )   :L0000,064A    MOV, X| T| DX'| MEM| 0794 L,
> ( 0000,0650 )                  MOV, X| F| AX'| ZO| [DX]
> ( 0000,0652 )                  MOV, X| T| AX'| ZO| [SI]
> ( 0000,0654 )                  LEA, DX'| ZO|    [DX +1* CX]
> ( 0000,0657 )                  LEA, SI'| BO| [SI] 4 B,
> ( 0000,065A )                  MOV, X| F| DX'| MEM| 0794 L,
> ( 0000,0660 )                  RET,
> ( 0000,0661 )   :X_z,    MOVI|X, CX| 1 IL,
> ( 0000,0666 )                  JMPS, L0000,064A RB,
> ( 0000,0668 )   :X_j,    MOVI|X, CX| 2 IL,
> ( 0000,066D )                  JMPS, L0000,064A RB,
> ( 0000,066F )   :X_3,    MOVI|X, CX| 3 IL,
> ( 0000,0674 )                  JMPS, L0000,064A RB,
> ( 0000,0676 )   :X_;    MOV, X| T| DX'| MEM| 0794 L,
> ( 0000,067C )                  SUBSI, R| DX| 5 IS,
> ( 0000,067F )                  CMP, X| F| DX'| MEM| 07A0 L,
> ( 0000,0685 )                  J, Z| N| L0000,068F RB,
> ( 0000,0687 )                  CMPI, B| ZO| [DX] 0E8 IB,
> ( 0000,068A )                  J, Z| N| L0000,068F RB,
> ( 0000,068C )                  INC, B| ZO| [DX]
> ( 0000,068E )                  RET,
> ---------------------------
> 
> Can someone shed some light on this?
> It is difficult to get a "second opinion" from colorforth
> itself, as the z and j are not used in kernel words.
> 
> I use strings as compact Huffman tables in the following code,
> (ANSI apart from the strings).
> 
> [To turn the Stallman convention into a stack diagram,
>   replace return with --
>   surround with ( )
>   keep only upper case words ]
> ___________________________________
> \ Throughout the following: colorname means a machine word with a
> \ huffman encoded name a la colorforth.
> 
> DECIMAL
> \ Offsets in these strings are the Huffman code for 4,5 and 7 length
> \ chars, exclusive the Huffman determination prefix.
> " rtoeani" DROP CONSTANT C4
> "smcylgfw" DROP CONSTANT C5
> "dvpbhxuqkzj34567891-0.2/;:!+@*,?" DROP CONSTANT C7
> 
> \ For a COLORNAME, return a COLORNAME without its first char, and that CHAR.
> : UNPACK
>     DUP 0< 0= IF
>         DUP   4 LSHIFT SWAP
>         28 RSHIFT  C4 + C@
>     ELSE 1 LSHIFT DUP 0< 0= IF
>         DUP   4 LSHIFT SWAP
>         28 RSHIFT  C5 + C@
>     ELSE 1 LSHIFT
>         DUP   5 LSHIFT SWAP
>         27 RSHIFT  C7 + C@
>     THEN THEN ;
> 
> \ Copy COLORNAME to ``PAD'', return as (ascii) STRINGCONSTANT
> \ To not upset the disassembler with conflicting names colorforthnames
> \ are prepended with "X_".
> : CN>ASC  "X_" PAD $!   BEGIN UNPACK PAD $C+ DUP 0= UNTIL DROP   PAD $@ ;
> 
> \ Print out a COLORNAME.
> : .WORD   CN>ASC TYPE ;
> ___________________________________
> 
> --
> Albert van der Horst,Oranjestr 8,3511 RA UTRECHT,THE NETHERLANDS
> Economic growth -- like all pyramid schemes -- ultimately falters.
> [email protected] http://home.hccnet.nl/a.w.m.van.der.horst
> 
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> 
> 

ras
-- 
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