Minimal Brainfuck interpreter

A minimal Brainfuck interpreter implemented in ANSI C that evaluates Brainfuck source code and writes output to a provided FILE stream.

Description

The function mbfi_eval interprets Brainfuck code encoded as a sequence of token characters (macros from mbfi.h) and operates on a contiguous tape buffer allocated. The function advances through code, updates the tape, handles loops, performs I/O, and writes printed characters to the supplied FILE *output.

Behavior summary:

• BF_ADD / BF_SUB: increment/decrement current cell
• BF_ARI / BF_ALE: move tape pointer right/left
• BF_BLE / BF_BRI: loop start/end handling (skips or rewinds to matching bracket)
• BF_PUTCH: write current cell as char to output and flush
• BF_GETCH: read a char from stdin into current cell
• Non-token characters are ignored
• Allocated tape is freed before returning

API usage example

#include <stdio.h>
#include <mbfi.h>

int main(void) {
    char *program = "++>+<[->+<].";
    mbfi_eval(program, stdout);
    return 0;
}

CLI usage examples

Run the program reading input from specified file:

$ mbfi ~/dev/src/bf/program.bf

Run the program reading input piped from stdin:

$ cat ~/dev/src/bf/program.bf | mbfi -

License

• MIT License
• Copyright (c) 2018-2025, J. A. Corbal
• Read the file LICENSE for more details