Brainfuck interpreter

beer.b

;; 99 bottles of beer on the wall
;; warning: alcohol destroys brain cells! (not as much as brainfuck)
;; written by Keymaker


  ++++[>+++++<-]>+++
  [
    [>+>+<<-]
    >++++++[<+>-]+++++++++[<++++++++++>-]
    >[<+>-]<-
  ]
  +++>+++++++++[<+++++++++>-]
  >++++++[<++++++++>-]<--[>+>+<<-]>>[<<+>>-]<--
  >>++++[<++++++++>-]++++++++++

  >+++++++++[>+++++++++++<-]>
  [
    [>+>+>+<<<-]>[<+>-]>>
    [
      [>+>+<<-]>>[<<+>>-]<
      [<->-[<->-[<->-[<->-[<->-[<->-[<->-[<->-[<->-[<<<+>---------->->[-]]]]]]]]]]]<
    ]
    <<[>>++++++++++++[<++++<++++>>-]<<[.[-]>]<<]
    >[<++++++[>++++++++<-]>.[-]]<<

    <<<.<<<<<.[<]>>>>>>>>>.<<<<<..>>>>>>>>.>>>>>>>.

    [>]>[>+>+<<-]>[<+>-]>[-[[-]+++++++++[<+++++++++++++>-]<--.[-]>]]<<

    <<<.[<]>>>>>>>>>.>>>>>>>>>.[>]<<.<<<<<.<<<..[<]>>>>>>.[>]<<.
    [<]>>>>>>>>>.>.[>]<<.[<]>>>>.>>>>>>>>>>>>.>>>.[>]<<.
    [<]>.[>]<<<<<<.<<<<<<<<<<<..[>]<<<.>.

    [>]>[>+>+>+<<<-]>[<+>-]>>
    [
      [>+>+<<-]>>[<<+>>-]<
      [<->-[<->-[<->-[<->-[<->-[<->-[<->-[<->-[<->-[<<<+>---------->->[-]]]]]]]]]]]<
    ]
    <<[>>++++++++++++[<++++<++++>>-]<<[.[-]>]<<]
    >[<++++++[>++++++++<-]>.[-]]<<

    <<<.<<<<<.[<]>>>>>>>>>.<<<<<..>>>>>>>>.>>>>>>>.

    [>]>[>+>+<<-]>[<+>-]>[-[[-]+++++++++[<+++++++++++++>-]<--.[-]>]]<<

    <<<.[<]>>>>>>>>>.>>>>>>>>>.[>]<<.<<<<<.<<<..[<]>>>>>>.[>]<<<<.>>>.

    <<<<.<.<<<<<<<<<<.>>>>>>.[>]<<.[<]>>>>>>>>>.>.>>>>>>>>>.[>]<<.
    <<<<<<<.[<]>>>>>>>>>.[<]>.>>>>>>>>>.[>]<<.<<<<.<<<<<<<<<<<<<.[>]<<<<<<<<<.
    [>]<<.[<]>>>>>>>>.[>]<<<<<<.[<]>>>>>..[>]<<.<<<<<<<<<<<<.[<]>>>>.
    [>]<<.<<<<.[<]>>>>>>.>>>.<<<<<<.>>>>>>>.>>>>>>>>>>.[>]<<<.>.

    >>>-

    [>+>+>+<<<-]>[<+>-]>>
    [
      [>+>+<<-]>>[<<+>>-]<
      [<->-[<->-[<->-[<->-[<->-[<->-[<->-[<->-[<->-[<<<+>---------->->[-]]]]]]]]]]]<
    ]
    <<[>>++++++++++++[<++++<++++>>-]<<[.[-]>]<<]
    >[<++++++[>++++++++<-]>.[-]]<<

    [>+>+<<-]>[<+>-]+>[<->[-]]<
    [-<<<[<]>>>>>>>>>>.<.[>]<<.[<]>>>>>>>>>>>.<<.<<<.[>]<<<<<<<<<<.[>]>>]<

    <<<.<<<<<.[<]>>>>>>>>>.<<<<<..>>>>>>>>.>>>>>>>.

    [>]>[>+>+<<-]>[<+>-]+>
    [<->-[<+>[-]]]<
    [++++++++[>+++++++++++++<-]>--.[-]<]<

    <<<.[<]>>>>>>>>>.>>>>>>>>>.[>]<<.<<<<<.<<<..[<]>>>>>>.[>]<<.
    [<]>>>>>>>>>.>.[>]<<.[<]>>>>.>>>>>>>>>>>>.>>>.[>]<<.
    [<]>.[>]<<<<<<.<<<<<<<<<<<..[>]<<<<.>>>..

    >>
  ]

brainf.sh

#!/bin/sh

ascii=0
while getopts a name ; do
    case $name in
        a) ascii=1 ;;
    esac
done

shift $(expr $OPTIND - 1)

cat $1 | awk '
BEGIN {
    RS="\0"; FS=""; p=0; inputp=0; mem[0]=0; ascii='$ascii';
} {
    for(i = 0; i != NF ; ++i)
        input[i]=$(i+1);
    end=NF;

} END {
    while(inputp != end) {
        if(input[inputp] == ">") {
            p++;
            if(mem[p]=="") mem[p]=0;

        } else if(input[inputp] == "<") {
            if(p == 0) {
                print "Error: decrementing out of range";
                exit;
            }
            p--;
            if(mem[p]=="") mem[p]=0;

        } else if(input[inputp] == "+") {
            if(mem[p]==255) mem[p]=0;
            else mem[p]++;
        } else if(input[inputp] == "-") {
            if(mem[p]==0) mem[p]=255;
            else mem[p]--;
        } else if(input[inputp] == ".") {
            if(ascii == 1)
                printf("%c", mem[p]);
            else
                printf("%d ", mem[p]);
        } else if(input[inputp] == "[") {
            if(mem[p] == 0) {
                level = 0;
                for(;;) {
                    if(inputp == end-1) {
                        print "Error: non-matching right bracket";
                        exit;
                    }

                    inputp++;
                    if(input[inputp] == "[")
                        level++;
                    else if(input[inputp] == "]") {
                        if(level == 0) break;
                        level--;
                    }
                }
            }
        } else if(input[inputp] == "]") {
            if(mem[p] != 0) {
                level = 0;
                for(;;) {
                    if(inputp == 0) {
                        print "Error: non-matching left bracket";
                        exit;
                    }

                    inputp--;
                    if(input[inputp] == "]")
                        level++;
                    else if(input[inputp] == "[") {
                        if(level == 0) break;
                        level--;
                    }
                }
            }
        }

        inputp++;
    }

    if(ascii == 0) {
        ORS="\n";
        print "";
    }
}'

factorial.b

;; factorials
;; this program prints out the sequence of factorials
;; written by Keymaker
;; does not terminate by itself


  ++++++++++>>>+>>>>+>+<[[+++++[>++++
  ++++<-]>.<++++++[>--------<-]+<<]<<
  [<<]<.>>>>+<[->[<+>-[<+>-[<+>-[<+>-
  [<+>-[<+>-[<+>-[<+>-[<+>-[<[-]>-+>[
  <->-]<[->>>[>>]<<[->[>>+<<-]>+<<<<]
  <]>[-]+>+<<]]]]]]]]]]<[>+<-]+>>]<<[
  <<]>>[->>[>>]>>[-<<[<<]<<[<<]>[>[>>
  ]>>[>>]>>[>>]>+>+<<<<[<<]<<[<<]<<[<
  <]>-]>[>>]>>[>>]>>[>>]>[<<<[<<]<<[<
  <]<<[<<]>+>[>>]>>[>>]>>[>>]>-]<<<[<
  <]>[>[>>]>+>>+<<<<<[<<]>-]>[>>]>[<<
  <[<<]>+>[>>]>-]>>[<[<<+>+>-]<[>>>+<
  <<-]<[>>+<<-]>>>-]<[-]>>+[>[>>>>]>[
  >>>>]>[-]+>+<[<<<<]>-]>[>>>>]>[>>>>
  ]>->-[<<<+>>+>-]<[>+<-]>[[<<+>+>-]<
  [<->-[<->-[<->-[<->-[<->-[<->-[<->-
  [<->-[<->-[<-<---------->>[-]>>>>[-
  ]+>+<<<<<]]]]]]]]]]<[>>+<<-]>>]<+<+
  <[>>>+<<<-]<<[<<<<]<<<<<[<<]+>>]>>>
  >>[>>>>]+>[>>>>]<<<<[-<<<<]>>>>>[<<
  <<]<<<<<[<<]<<[<<]+>>]>>[>>]>>>>>[-
  >>>>]<<[<<<<]>>>>[>>>>]<<<<<<<<[>>>
  >[<<+>>->[<<+>>-]>]<<<<[<<]<<]<<<<<
  [->[-]>>>>>>>>[<<+>>->[<<+>>-]>]<<<
  <[<<]<<<<<<<]>>>>>>>>>[<<<<<<<+>>>>
  >>>->[<<<<<<<+>>>>>>>-]>]<<<<<<<<<]

helloworld.b

++++++++++[>+++++++>++++++++++>+++>+<<<<
-]>++.>+.+++++++..+++.>++.<<++++++++++++
+++.>.+++.------.--------.>+.>.