[ColorForth] More newbie questions

[Leslie Snively <les@xxxxxxxxxxxxxx>]

On Friday, September 28, 2001, at 07:53 , Mark Slicker wrote:

> '?' tests (and operation) the top element of the stack. For example you
> could write your 'iftest' as:
>
> : iftest -1 ? if 1 ; then 0 ;
>
> -1 tests all the bits. Also see Kris Johnson's word list which has a lot
> of words not documented on Chuck's site:

Thanks, Mark, this helps some, but not enough for my simple mind.  I've 
been using Kris' list of commands and one of the things colorForth 
doesn't seem to have many of are conditionals.  Since your description 
of what "if" needs to behave correctly on the Pentium is the indirect 
effect of a conditional, what's the mechanism for setting the flags?  
(In the working code I'm developing I do an arithmetic operation 
immediately before the "if", as you suggest, with the intent of 
branching on a zero or not zero outcome.  But it appears not to effect 
the zero flag so the "if" is not doing what I would expect.)  I expect 
that there are other ways to accomplish this function in colorForth that 
I'm not familiar with or not clever enough to have sorted out yet.  Any 
hints are appreciated.

Mark, could you expand on what the result is of "?" testing bits?  My 
playing with it, and Kris' description on his site suggests that it does 
an "and" but the result effects the value of the zero flag.  Is this the 
preferred or recommended mechanism for growing our own conditionals?  I 
see that Chuck uses a word "less" in some places, in a context that 
suggests to me that it is a conditional that effects the zero flag as 
well.  It doesn't show up in any of the documentation nor could I find 
it in the code blocks, so I assume it's the conditional "less than".  Is 
that a valid assumption based on your experience?  Are you aware of 
others that are similar?
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