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Date: Fri, 15 Feb 2008 20:49:06 +0000
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To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Subject: Re: [9fans] Google search of the day
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I think the stack direction is just for the pseudocode, the stack in my
implementation grew down, it depends  on what assembler primitives are
available I guess
>>
>>
>> moddiv:
>>     colon
>>     divmod
>>     swop
>>     semi
>
> I am genuinely lost, do not understand a word of it.


colon tells the inner loop that this is a set of other Words (addresses)
not machine instructions
so the loop will execute
divmod (which does division with modulous and leave the divsor,  mod on
the stack)
swop then reverses the order of the top two stack items
semi then jumps to semi to pop the next I before jumping to it

It gives you an interactive compiler without linking as you can add new
Words at runtime

:square dup *

would put
square :
    colon
    dup
   multiply
   semi

somewhere in memory (called the dictionary)

My version uses two stacks, one for args and one for addresses

for more analysis I suggest some online reading, I'm not deep enough
into either paradigm to offer suitable insights