Execute Brain****/C

From Rosetta Code
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.

/* This is the Neutron brainfuck interpreter.
* It's rather small and dense, but still readable, more or less.
*
* Robert de Bath -- 2013.
*/

#include <stdio.h>
#include <stdlib.h>
#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;
}

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