#include <stdio.h>
#include <assert.h>

void run(const char* bytecode, int start, int stop, int step) {
  // interpreter state (e.g. registers)
  int pc = 0;
  int top;
  int current = start;
  int col = 0;
  int row = 0;

  // interpretive loop
  while (bytecode[pc]) {
    char c = bytecode[pc++];
    if (c == '\n') {
      col = 0;
      row += 1;
    }
    // interpretive dispatch
    if (c != '%') {
      putchar(c); // opcode
    } else {
      switch (bytecode[pc++]) {
      case '[': top = pc; break; // opcode
      case ']': pc = current > stop ? pc : top; break; // opcode
      case 'i': printf("%d", current); current += step; break; // opcode
      case 'r': printf("%d", row); break; // opcode
      case 'c': printf("%d", col++); break; // opcode
      case '%': putchar('%'); break; // opcode
      default: assert(0); break;
      }
    }
  }
}

int main(int argc, char* argv[]) {
  // program to be interpreted
  run("\tcol%c\tcol%c\tcol%c\n%[row%r:\t%i,\t%i,\t%i\n%]", 10, 30, 3);
  return 0;
}