bf.c

/* The world's smallest Brainfuck interpreter in C, by Kang Seonghoon
 * http://j.mearie.org/post/1181041789/brainfuck-interpreter-in-2-lines-of-c */
s[99],*r=s,*d,c;main(a,b){char*v=1[d=b];for(;c=*v++%93;)for(b=c&2,b=c%7?a&&(c&17
?c&1?(*r+=b-1):(r+=b-1):syscall(4-!b,b,r,1),0):v;b&&c|a**r;v=d)main(!c,&a);d=v;}

How does this work? :O

To any newcomers:

Compile using gcc with the flag "-m32"

You may need to install the gcc-multilib package in order to target an x86 binary

After you have the right libraries installed, you should be able to compile like this:

gcc -m32 -o bf bf.c

good stuff.

Here is the clarified version. I used gpt-4 to reconstruct the code, meaning I just wanted to share the clarified version for learning purposes. I don't know C language, but I was curious.

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#define TAPE_SIZE 30000

// Declare an array to act as the tape for Brainfuck. Initialize all to zero.
unsigned char s[TAPE_SIZE] = {0};

// This will be the data pointer used in Brainfuck
unsigned char* ptr = s;

// Forward declaration of the main function to make it recursive
int main(int argc, char *argv[]);

int main(int argc, char *argv[]) {
  char* v;

  // Ensure that a Brainfuck program is provided as an argument
  if (argc != 2) {
    fprintf(stderr, "Usage: %s 'brainfuck_code'\n", argv[0]);
    return 1;
  }

  v = argv[1];

  while (*v) {
    switch (*v) {
      case '>':
        ptr++;
        // Boundary check to prevent going beyond the tape
        if (ptr >= s + TAPE_SIZE) {
          fprintf(stderr, "Error: Pointer out of bounds\n");
          return 1;
        }
        break;
      case '<':
        // Boundary check to prevent going before the tape
        if (ptr <= s) {
          fprintf(stderr, "Error: Pointer out of bounds\n");
          return 1;
        }
        ptr--;
        break;
      case '+':
        (*ptr)++;
        break;
      case '-':
        (*ptr)--;
        break;
      case '.':
        putchar(*ptr);
        break;
      case ',':
        *ptr = (unsigned char)getchar();
        break;
      case '[':
        if (!*ptr) {
          int loop = 1;
          while (loop > 0) {
            v++;
            if (*v == '[') loop++;
            if (*v == ']') loop--;
          }
        }
        break;
      case ']':
        if (*ptr) {
          int loop = 1;
          while (loop > 0) {
            v--;
            if (*v == '[') loop--;
            if (*v == ']') loop++;
          }
        }
        break;
    }
    v++;
  }

  return 0;
}

How to compile?

gcc brainfuck.c

How to run?

./a.out "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
"

This should dispay

Hello world

Here is the clarified version. I used gpt-4 to reconstruct the code, meaning I just wanted to share the clarified version for learning purposes. I don't know C language, but I was curious.

Honestly looks like chat gpt just spat out a generic bf interpreter, it doesn't share many characteristics with the minimal interpreter.