ENDLESS TAPE BRAINFUCK INTERPRETER
                            ______________
__________________________ /              \ __________________________
   /   /   /   /   /   /  /      etbi      \  \   \   \   \   \   \
0 / 0 / 0 / 0 / 0 / 0 / 0/__________________\0 \ 0 \ 0 \ 0 \ 0 \ 0 \ 0
_/___/___/___/___/___/___|                  |___\___\___\___\___\___\_
                         |     +-<>.,[]     |
                         |__________________|

 a brainfuck interpreter featuring an endless tape in both directions

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etbi can interpret brainfuck source files with an endless tape of
cells with the size of a char, initially set to 0. Use it with `etbi
FILE', or run one of the built-in examples with `etbi -e NAME'. You
can always get help with `etbi --help'.

etbi also features an interactive REPL-like (Read Eval Print Loop)
mode, which you can access using `etbi -i'. In the interactive mode
you can easily test snippets of brainfuck code, after which the new
state of the tape is shown for easy debugging. The interactive mode
features a few other modes, which you can see by typing `!help'.

etbi implements a few simple optimizations:
- Movement contraction: multiple movement instructions following
  each other are added together to one instruction with an argument.
- Alteration contraction: multiple alteration instructions following
  each other are added together to one instruction with an argument.
- Clear loop optimization: loops which can only end with the current
  cell ending up empty such as '[-]' are converted to a single clear
  instruction which sets the current cell to 0.
- Scan loop optimization: loops which are scanning all cells in a
  direction until they find one set to 0, such as '[>]' are converted
  to a single instruction which uses memchr or memrchr to find one
  faster.

To install etbi simply run `./configure && make && sudo make install'.

etbi is licensed under the GPLv3+, see `COPYING' for the full license
text.