Execute Brain****/C

Execute Brain****/C is an implementation of Brainf***. Other implementations of Brainf***.

Execute Brain****/C is part of RCBF. You may find other members of RCBF at Category:RCBF.

This Brain**** interpreter has an eight bit cell size with the tape length bounded only by available memory. The normal cell expansion techniques work for brain**** programs that require a larger cell size (or you can just change the tape cell type).

It is a fairly slow interpreter which is probably able to run mandelbrot.b in about a minute on your machine.

<lang c>/* This is the Neutron brainfuck interpreter.

* It's rather small and dense, but still readable, more or less.
*
* Robert de Bath -- 2013.
*/

1. include <stdio.h>
2. include <stdlib.h>
3. include <string.h>

struct bfi { char cmd; struct bfi *next, *jmp; }; struct mem { char val; struct mem *next, *prev; };

int main(int argc, char **argv) {

   FILE * ifd;
   int ch;
   struct bfi *p=0, *n=0, *j=0, *pgm = 0;
   struct mem *m = calloc(1,sizeof*m);
   setbuf(stdout, NULL);

   /* Open the file from the command line or stdin */
   if (argc < 2 || strcmp(argv[1], "-") == 0) ifd = stdin;
   else if ((ifd = fopen(argv[1], "r")) == 0) { perror(argv[1]); exit(1); }

   /*
    *  For each character, if it's a valid BF command add it onto the
    *  end of the program. If the input is stdin use the '!' character
    *  to mark the end of the program and the start of the data, but
    *  only if we have a complete program.  The 'j' variable points
    *  at the list of currently open '[' commands, one is matched off
    *  by each ']'.  A ']' without a matching '[' is not a legal BF
    *  command and so is ignored.  If there are any '[' commands left
    *  over at the end they are not valid BF commands and so are ignored.
    */
   while((ch = getc(ifd)) != EOF && (ifd!=stdin || ch != '!' || j || !pgm)) {
       if (ch == '<' || ch == '>' || ch == '+' || ch == '-' ||
           ch == ',' || ch == '.' || ch == '[' || (ch == ']' && j)) {
           if ((n = calloc(1, sizeof*n)) == 0) {
               perror(argv[0]); exit(1);
           }
           if (p) p->next = n; else pgm = n;
           n->cmd = ch; p = n;
           if (n->cmd == '[') { n->jmp=j; j = n; }
           else if (n->cmd == ']') {
               n->jmp = j; j = j->jmp; n->jmp->jmp = n;
           }
       }
   }

   /* Ignore any left over '[' commands */
   while(j) { p = j; j = j->jmp; p->jmp = 0; p->cmd = ' '; }

   if (ifd!=stdin) fclose(ifd);

   /* Execute the loaded BF program */
   for(n=pgm; n; n=n->next)
       switch(n->cmd)
       {
           case '+': m->val++; break;
           case '-': m->val--; break;
           case '.': putchar(m->val); break;
           case ',': if((ch=getchar())!=EOF) m->val=ch; break;
           case '[': if (m->val == 0) n=n->jmp; break;
           case ']': if (m->val != 0) n=n->jmp; break;
           case '<':
               if (!(m=m->prev)) {
                   fprintf(stderr, "%s: Hit start of tape\n", argv[0]);
                   exit(1);
               }
               break;
           case '>':
               if (m->next == 0) {
                   if ((m->next = calloc(1,sizeof*m)) == 0) {
                       perror(argv[0]); exit(1);
                   }
                   m->next->prev = m;
               }
               m=m->next;
               break;
       }

   return 0;

}</lang>

This Brain**** interpreter is released into the Public domain or if your prefer the Creative commons CC0 license.