Re: [colorforth] Disassembling Pentium ColorForth

["Jeff Fox" <fox@xxxxxxxxxxxxxxxxxxx>]

I think this shows a difference between Pentium colorforth and MISC
because on the MISC machines I have used the -IF opcode branches when the
sign or carry bit is not set.  It is a branch if not negative, and
that includes 0.

I guess on Pentium colorforth -IF must not branch on 0 like it does
on MISC thus the -9 + instead of the -10 + that I would have expected
from MISC colorforth.

So on MISC to test for 0-9 or 10-15 I would do -10 +
0-9 becomes -10 to -1
10-15 becomes 0-5

you test sign or carry with -IF
if 0-5 you add the char "A"
if -10 to -1 you add the 10 back to get 0-9
and you add the char "0"
but you do just one + after the -IF

you use a ; after the second +

it packs into the same number of words either way
but it makes one path through the word 33% faster
(and will consume less power)

it is wasteful on MISC to fall through and do three +
at runtime

here it is a machineforth dialect that closely resembles
misc colorforth

: digit ( 0-15 -- "0"-"9"|"A"-"F")
 -10 +
 -if [ char 0 10 + ], + ;
 then [ char A ], + ;

The -if might pack into the same word as the first +
it depends on the opcode bit-width, optional short-literal
availability, any need for extra nop with +, and cell width etc.

It could be written as one line, but I think it is easier
to read.  I might put the + -IF on the same line if I knew it was
going to pack.

I am used to yellow to green color transition in colorforth
doing what the [ generate-number ], does above. Without that
it could be:

: digit ( n-n) -10 + -if 58 + ; then 65 + ;



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