[M3devel] add/subtract in Quake

[Olaf Wagner]

Shouldn't we rather define some standard quake functions and implement
them in M3, like add, substract, multiply, div, mod?
Probably working on TEXT of course... or even introduce a new
quake type for integers?

I haven't really thought about that, but I've missed integer arithmetics
several times in the past, too.

Olaf

Quoting Jay K <jay.krell at cornell.edu>:

> Folks might find this amusing or useful.    I actually think I'm   
> going to use it, just for the numbers 0-64.It implements addition   
> and subtraction for a fixed range, here 0-9999Global variables are   
> only used for initialization.Thereafter, just global constants (no   
> enforcement of that, but I think it could be done by having   
> initialization return them).
> Approach is that adding 1 to a single digit can be done with a small  
>  map.Adding 1 to multiple digits can be done using multiple  
> variables  and checking for "wraparound" to 0 (the table maps 9 to  
> 0).You count  up to 9999, filling in an Add1 and Sub1 hash table as  
> you go up.  I  don't think quake has an appropriate looping  
> mechanism, so counting  up to 9999 is done recursively.Then Add and  
> Sub are implemented  recursively like Add1{Add(a, Sub1(b)}.
>
> local Add1 = { }local Sub1 = { }
>
> local counter0 = 0local counter1 = 0local counter2 = 0local counter3 = 0
>
> local proc Increment() is  local inc = { 0:1,1:2,2:3,3:4,4:5,         
>          5:6,6:7,7:8,8:9,9:0 }  counter0 = inc{counter0}  if   
> equal(counter0, 0)    counter1 = inc{counter1}    if equal(counter1,  
>  0)      counter2 = inc{counter2}      if equal(counter2, 0)          
> counter3 = inc{counter3}      end    end  end  local c = ""  foreach  
>  d in [counter3, counter2, counter1, counter0]    if not equal(d, 0)  
>  or not equal(c, "")      c = c & d    end  end  return cend
>
> proc InitMath_F1(a, b) is  if equal(a, "9999")    return  end    
> Add1{a} = b  Sub1{b} = a  InitMath_F1(b, Increment())end
> proc InitMath() is  counter0 = 0  counter1 = 0  counter2 = 0    
> counter3 = 0  InitMath_F1(0, Increment())end
>
> proc Add(a, b) is  if equal(a, 0) return b end  if equal(b, 0)   
> return a end  if equal(a, 1) return Add1{b} end  if equal(b, 1)   
> return Add1{a} end  return Add1{Add(a, Sub1{b})}end
>
> proc Sub(a, b) is  if equal(a, 0) return b end  if equal(b, 0)   
> return a end  if equal(a, 1) return Sub1{b} end  if equal(b, 1)   
> return Sub1{a} end  return Sub1{Sub(a, Sub1{b})}end
>
> InitMath()write("99 - 40 is " & Sub(99, 40), CR)write("6 - 4 is " &   
> Sub(6, 4), CR)write("3 + 2 is " & Add(2, 3), CR)
-- 
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