Calculating the sum of a *lot* of primes

[Geoff Canyon]

I re-wrote the algorithm a bit to tweak for speed, then ran it successfully
for primes up to 3 billion (a couple hours), and got the wrong answer
because my big addition function was broken :-/

So I broke the problem in two: first generate the list of primes, then do
the addition.

For the primes I generated the list up to 100,000, stored that, and then
used a simpler (by one command) routine to generate the primes to 10
billion in a few hours. Here's that:

on mouseUp
   put the long seconds into ST
   repeat for each line i in line 2 to -1 of the primeList of this stack
      put 2*i & comma after P[i^2]
   end repeat
   put 2 into pList
   put fld "path" into fPath
   open file fPath for write
   put 0 into S
   put fld 1 into endPoint
   if endPoint mod 2 = 0 then subtract 1 from endPoint
   repeat with i = 3 to endPoint step 2
      if P[i] is empty then
         put cr & i after pList
      else
         repeat for each item x in P[i]
            put x & comma after P[i + x]
         end repeat
      end if
      if the seconds > S then
         put the seconds + 5 into S
         put i into fld 2
         write pList to file fPath
         put empty into pList
         unlock screen
         lock screen
      end if
      delete variable P[i]
   end repeat
   put i into fld 2
   write pList to file fPath
   close file fPath
   put the long seconds - ST
end mouseUp

That's ~5gb of primes...

Then I re-wrote the addition function to use a simpler, slower method,
tested it, and let it go. An hour or so later, and I had my answer
(validated against the site with the challenge). If anyone sees the problem
with bAdd, I'm all ears. I didn't look too closely, since I just wanted to
get the code running to solve the problem. It works for all the test cases
I tried, but it seems to fail on the boundary between 14 and 15 digit
numbers.


on mouseUp
   put fld "path" into fPath
   open file fPath for read
   put 0 into T
   put 0 into S
   repeat with C = 1 to 999999999999
      read from file fPath for 1 line
      if it > fld 1 then exit repeat
      put bAdd2(T,char 1 to -2 of it) into T
      if the seconds > S then
         put the seconds + 1 into S
         put T && it && C into fld 2
         unlock screen
         lock screen
      end if
   end repeat
   put T && it && C - 1 into fld 2
   close file fPath
end mouseUp

function bAdd x,y
   put 0 into c
   repeat with i = 14 to max(length(x),length(y)) step 14
      add char -i to 13 - i of x + char -i to 13 - i of y to c
      put char -14 to -1 of c before r
      delete char -14 to -1 of c
   end repeat
   return c & r
end bAdd

function bAdd2 x,y
   put 0 into c
   repeat with i = 1 to max(length(x),length(y))
      put char -i of x + char -i of y + c into c
      put char -1 of c before r
      delete char -1 of c
   end repeat
   return c & r
end bAdd2