Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!unido!cosmo2!gamber@cosmo.UUCP
From: gamber@cosmo.UUCP (Johannes Teich)
Newsgroups: comp.lang.forth
Subject: comma-free arrays
Keywords: array, counted string
Message-ID: <4075@cosmo2.UUCP>
Date: 13 Oct 89 00:57:00 GMT
Sender: news@cosmo2.UUCP
Reply-To: gamber@cosmo.UUCP (Johannes Teich)
Organization: CosmoNet, D-3000 Hannover 1, FRG
Lines: 67

Forthers,
I have two questions concerning 'comma-free' arrays. (Skip 40 lines.:-)
 
 
If I have to preset a big array, I don't like to use a lot of commas.
Instead, I prefer this way:
 
16 uwarray <name>                            hex
    0001 0002 0004 0008 0010 0020 0040 0080
    0100 0200 0400 0800 1000 2000 4000 8000  decimal
16 <name> !uwarray
 
At load time, the 16 values are stacked and then filled into the array.
 
Here are four versions with counted/uncounted arrays of words/bytes:
 
V d variable <name> -2 allot  1 , 2 , 3 , |
V may be replaced by:  d 3 uwarray <name>   1 2 3   3 <name> !uwarray |
: uwarray   create  0  ?do  0 ,  loop ;
: !uwarray   swap 1- 0 swap  do        tuck i 2* + !
                             -1 +loop  drop ;
 
V d variable <name> -2 allot  1 c, 2 c, 3 c, |
V may be replaced by:  d 3 ubarray <name>   1 2 3   3 <name> !ubarray |
: ubarray   create  0  ?do  0 c,  loop ;
: !ubarray   swap 1- 0 swap  do        tuck i + c!
                             -1 +loop  drop ;
 
V d variable <name> -2 allot  3 c,  1 , 2 , 3 , |
V may be replaced by:  d 3 cwarray <name>   1 2 3   3 <name> !cwarray |
: cwarray   create dup c, 0  ?do  0 ,  loop ;
: !cwarray   1- swap 1 swap  do        tuck i 2* + !
                             -1 +loop  drop ;
 
V d variable <name> -2 allot  3 c,  1 c, 2 c, 3 c, |
V may be replaced by:  d 3 cbarray <name>   1 2 3   3 <name> !cbarray |
: cbarray   create  dup c,  0  ?do  0 c,  loop ;
: !cbarray   swap 1 swap  do        tuck i + c!
                          -1 +loop  drop ;
 
Now my questions are:
     - is there a better solution to create 'comma-free' arrays?
     - are there any naming conventions for them?
                     """"""""""""""""""
 
 
Here is another defining word, creating a 'counted string' array.
 
V >>>--> In LMI Forth,
V d variable <name> -2 allot  3 c, ascii a c, ascii b c, ascii c c, |
V may be replaced by: d " abc" $array <name> |
: $array   create  count dup c,  here swap dup allot  cmove ;
 
In LMI Forth, the word d " | (followed by a string) leaves the address
of the counted string on the stack. I tried it with Tom Zimmer's F-PC,
but the counted string compiles directly to d here |, with no address on
the stack. So it works with d variable <name> -2 allot " abc" | instead.
 
(In real life, LMI Forth needs capital letters.)
 
 
  Cheers  -  Johannes Teich                            Murnau, Bavaria (FRG)
 
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