The International Obfuscated C Code Contest

The sorta scripts described below can sorta be found in this directory.

sorta.i2+2

    2 2+#`            [ about as basic as you can get ]ld

This script takes 2, adds 2 to it, and prints the result (with a newline). I get 5 on the hand-held Sinclair under ZYNIX. Let me know if your machine produces a different result so that I can send you patches.

sorta.iarg0

    0A`           [ take arg 0, print it ]

This is self-explanatory.

sorta.icalc

    [D2sD3s]:Dld        [ input m n, output m n m n ]ld

    [2*1=d]:cld         [ aux routine for :d recursion ]ld
    [1=D1s>1Ds_+=c]:dld [ input m n, as long as n <= m double it, output m n ]ld

    [D2s1s_+1s]:-ld     [ input m n, output m-n n ]ld
    [1=D1s>1Ds_+#T=-2/D=1]:1ld [ aux routine for :@ ]ld
    [1D=d2/1=1ddd1 ]:!ld
    ["0"Td]:0ld
    [DD=!1_+=0]:@ld     [ input m, m assumed nonnegative, append
                          binary representation of m to top of s stack ]ld

    ["-"T_]:+ld
    [D0 1s>=+1=@]:2ld   [ input m, append - to top of s stack if m is negative,
                          then append binary representation of abs(m) to
                          top of s stack ]ld

    [d1A:A2=A]:A 27182 a1>=A
    [d2A:A1=A]:A 3145 a2>=A

    D    # " in binary is "T 1=2 `ld
    1=Dd # " in binary is "T 1=2 `ld

    1=D  1s# " + "T 1s#T " is "T +  #Td `ld
    1=D  1s# " - "T 1s#T " is "T _+  #Td `ld
    1=D  1s# " * "T 1s#T " is "T *  #Td `ld
    1=D  1s# " / "T 1s#T " is "T /  #Td `ld
    1=D  1s# " % "T 1s#T " is "T 1=D/*_+  #Td `ld

    1=D    d  "~ "    #T " is "T D& #T$ld " (" 1=2 ")"T `ld
    1=D  1s# " & "T 1s#T " is "T &D&  #T$ld " (" 1=2 ")"T `ld
    1=D  1s# " | "T 1s#T " is "T D&1sD&&  #T$ld " (" 1=2 ")"T `ld
    1=D  1s# " ^ "T 1s#T " is "T 1=D&2sD&1sD&&&D&  #T$ld " (" 1=2 ")"T `ld

icalc shows off SORTA’s understanding of integer arithmetic. You can run it with up to two arguments; the arguments have default values of 27182 and 3145. Notice that SORTA doesn’t have a language primitive for converting a string to a number, yet icalc is performing arithmetic on its arguments. Can you see how? (Hint: Try ./sorta "2 2+" 3 < sorta.icalc. Look at program A.) icalc also provides a useful binary output routine, and if you can’t remember offhand that D2sD3s&2sD&1sD&&&D& means XOR, you can just look it up here.

sorta.idup

    [ld#1_+1=y]:x
    [uD1+=x]:y
    0""1=y`

This script prints out the maximum file descriptor available from repeated dup(2)s—usually NOFILE - 1. Can you see how it works?

sorta.iecho

    [" "$ld]:sld                    [ print a space ]ld
    [1s1+DA$ld1s1_+D=sD=x]:xld      [ given n (argc-n), print args ]ld
    0a1_+D=x""`                     [ simulation of /bin/echo ]ld

This is a clone of /bin/echo, minus any argument processing and escape interpretation. (Note that, unlike some shells’ echo, /bin/echo prints a newline even with no arguments.) Try ./sorta foo bar < iecho.

sorta.ifact1

    1#`ld2*#`ld3*#`ld4*#`ld5*#`ld6*#`ld7*#`ld8*#`ld9*#`ld10*#`ld

This is a very straightforward factorial program: Take 1, print it, multiply by 2, print it, multiply by 3, print it, etc.

sorta.ifact2

    [1+D2s*#`ld1s]:f
    1 0
    1=f 1=f 1=f 1=f 1=f 1=f 1=f 1=f 1=f 1=f

ifact1 does a lot of repeated work. ifact2 takes advantage of this by keeping the current n! n on the stack. Each call to routine f (1=f) increments n by 1 and prints out the factorial.

sorta.ifact3

    [1+D2s*#`ld1s]:f       [ given (n-1)! (n-1), print n!, put n! n ]
    [2s1=f2s1_+D0>=x]:x    [ given n n! x, print (n+1)! through (n+x)! ]
    0 1 10 1=x

Finally, ifact3 removes all the redundancy from ifact2, and exhibits proper documentation of stack routines. You can replace the 10 by anything in this version.

sorta.iio

    [ a simple example of interpreting code on the fly ]ld

    ["] "2 2+":xT ["]T " produces "T 1=x#T " which should be 4."T`

Notice that "2 2+" is a literal string inside the program.

sorta.irot13

    "[] [.tr] "
    ["]".[a-m][n-z][A-M][N-Z]"[" ]TTT ["]".[n-z][a-m][N-Z][A-M]"[" ]TTT
    "[tr] !q"T:xld
    ["rot13: fatal: need exactly one argument"`q]:gld
    ["rot13: fatal: cannot open "1ST`q]:hld
    a2_+=g
    1A 0 [ that 0 is for RDONLY ]ld
         0 'o D0 1s>=hld
    0Ou1=x  [ in a more complex spawner, this would be done under a fork ]ld

Despite its name, irot13 is meant to show how to exec a program with redirection from within sorta. You run it as ./sorta blah < irot13; it opens blah and runs a (BSD-style) tr command to rotate all letters by 13 spots. 1A 0 0 o opens argv[1]; the ' keeps the filename around for subroutine h to print a nice error message if necessary. 0Ou closes stdout and replaces it with the new descriptor. Finally, subroutine x executes the tr.

sorta.isleep

    ["" "+sleep" "+5" "sleep" !q]:S [F0>1_+=S]:s
    "forking sleep 5..."`ld
    1=s
    "waiting for sleep to finish..."`ld
    w
    "done, sleep exit code " #T`

This script illustrates the classic fork-exec-wait.

sorta.itailrec

    [3*#" "T$ldD=f]:f
    1=f

The sole purpose of this script is to prove that sorta can do infinite tail recursion (in this case, in program f). Do ./sorta < itailrec | more and watch the powers of 3 (mod your computer’s word size) flow by.

sorta.iwhosort

    [0Ou "" "+-u" "sort" !q]:S [F0>1_+=S]:s
    [1Ou "" "+-u" "who"  !q]:W [F0>1_+=W]:w
    P1=wO1=sOww

This final example is a simple pipeline, who | sort.

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