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From: dxf <dxforth@gmail.com>
Newsgroups: comp.lang.forth
Subject: Re: Roman numerals , recognizer "0r".
Date: Mon, 9 Jun 2025 13:42:51 +1000
Organization: i2pn2 (i2pn.org)
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On 9/06/2025 2:07 am, dxf wrote:
> On 9/06/2025 12:41 am, LIT wrote:
>> 0 VARIABLE FORMER
>> 0 VARIABLE PRESENT
>>
>> HERE 73 C, 86 C, 88 C, 76 C, 67 C, 68 C, 77 C,  \ I  V  X  L  C  D  M
>> HERE  0 C, 1 C, 2 C, 10 C, 20 C, 100 C, 200 C,
> ... 
> Yep. Nothing better than FigForth :)  How about ...
> 
> : CREATE  0 VARIABLE -2 ALLOT ; 

Actually CREATE wasn't needed here...

VARIABLE FORMER
VARIABLE PRESENT

HERE 73 C, 86 C, 88 C, 76 C, 67 C, 68 C, 77 C,  \ I  V  X  L  C  D  M
HERE  0 C, 1 C, 2 C, 10 C, 20 C, 100 C, 200 C,
CONSTANT ESYM  CONSTANT SYM

: VAL ( ch -- u )
  0  SWAP  ESYM SYM DO
   DUP I C@ =
   IF  DROP I 7 + C@ DUP 0= ABS SWAP 5 * +  NIP 1 SWAP LEAVE  THEN
 LOOP
 OVER IF NIP ELSE DROP THEN ;

: ROMAN>ARABIC ( addr count -- u )
 0 -ROT  0 FORMER !  0 PRESENT !
 OVER + 1- DO
   I C@ VAL  DUP PRESENT !
   DUP FORMER @ <
   IF    -
   ELSE  DUP FORMER ! +
   THEN
 -1 +LOOP ; 

S" MCMLIX" ROMAN>ARABIC . 1959  ok