bf.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include <stdio.h>
   4 #include <errno.h>
   5
   6 #define die(s, as...) {fprintf(stderr, s, ## as); return EXIT_FAILURE;}
   7 #define check_fail(v, s, f) if((v) == f) die("%s(): %s\n", s, strerror(errno))
   8 #define check_null(v, s) check_fail(v, s, NULL)
   9
  10 #define INITIALBUFSIZE 2
  11
  12 struct cs {
  13         long pl;
  14         struct cs *next;
  15 };
  16
  17 int main(int argc, char *argv[])
  18 {
  19         size_t offset, bufsize, depth;
  20         char *buf, *ptr;
  21         struct cs *temp, *cs;
  22         FILE *in;
  23
  24         if(argc != 2)
  25                 die("Usage: %s PROGRAM\n", argv[0]);
  26
  27         check_null(in = fopen(argv[1], "r"), "fopen");
  28         check_null(buf = calloc(bufsize = INITIALBUFSIZE, 1), "calloc");
  29         ptr = buf;
  30
  31         while (1){
  32                 switch (fgetc(in)){
  33                 case EOF:
  34                         free(buf);
  35                         check_fail(fclose(in), "fclose", -1);
  36                         return EXIT_SUCCESS;
  37                 case '>':
  38                         if (++ptr >= buf+bufsize){
  39                                 offset = ptr-buf;
  40                                 check_null(buf = realloc(buf, bufsize *=2),
  41                                         "realloc");
  42                                 ptr = buf+offset;
  43                                 memset(ptr, 0, bufsize/2);
  44                         }
  45                         break;
  46                 case '<':
  47                         if (ptr-- == buf)
  48                                 die("There is no stack position -1\n");
  49                         break;
  50                 case '+':
  51                         ++*ptr;
  52                         break;
  53                 case '-':
  54                         --*ptr;
  55                         break;
  56                 case '.':
  57                         putchar(*ptr);
  58                         break;
  59                 case ',':
  60                         *ptr = getchar();
  61                         break;
  62                 case '[':
  63                         if (*ptr){
  64                                 temp = cs;
  65                                 check_null(cs = malloc(sizeof(struct cs)),
  66                                         "malloc");
  67                                 cs->next = temp;
  68                                 check_fail(cs->pl = ftell(in), "ftell", -1);
  69                         } else {
  70                                 depth = 1;
  71                                 while (depth > 0){
  72                                         switch (fgetc(in)){
  73                                         case ']':
  74                                                 depth--;
  75                                                 break;
  76                                         case '[':
  77                                                 depth++;
  78                                         }
  79                                 }
  80                         }
  81                         break;
  82                 case ']':
  83                         check_fail(fseek(in, cs->pl-1, SEEK_SET), "fseek", -1);
  84                         temp = cs;
  85                         cs = cs->next;
  86                         free(temp);
  87                 }
  88         }
  89 }