#include <stdio.h>
#include <unistd.h>
#define c g->code
#define p g->pointer
#define f g->file
#define b g->bit

struct Data {
  const char *code;
  char vars[30000];
  char *pointer;
  char bit;
  FILE *file;
};

void lexer(struct Data *g) {
  const char *cc = c;
  while(*c)
    switch (*c++) {
      case '>':
        ++p;
        break;

      case '<':
        --p;
        break;

      case '+':
        ++*p;
        break;

      case '-':
        --*p;
        break;

      case '.':
        putchar(*p);
        break;

      case ',':
        *p = getchar();
        break;

      case '[':
        cc = c;
        if(!*p) while(*c++ != ']');
        while(*p) {
          c = cc; // restore char position to start of loop
          lexer(g);
        }
        break;

      case ']':
        return;

      case ':':
        printf("%hhd", *p);
        break;

      case ';':
        scanf("%hhd", p);
        break;

      case '#':
        // open in read mode unless the cell is 1
        if(f) fclose(f);
        f = fopen(p + 1, *p == 1 ? "w" : "r");
        break;

      case '`':
        *p = fgetc(f);
        break;

      case '!':
        fputc(*p, f);
        break;

      case '\'':
        *p ^= (1 << b);
        b <= 0 ? b = 7 : b--;
        break;

      case '"':
        b <= 0 ? b = 7 : b--;
        break;

      case '\\':
        while(*c++ != '\n');
        break;

      case '@':
        printf("%hhd : %hhd : %hhd : %hhd : %hhd", *(p - 2), *(p - 1), *p, *(p + 1), *(p + 2));
        break;

      case '$':
        sleep(*p);
        break;

      default:
        // everything else is comments
        break;
    }
}
/*
 * Usage:
 *  struct Data g;
 *  g.code = "code here";
 *  g.bit = 7;
 *  g.pointer = &g.data[15000];
 *  lexer(&g);
 */