有高手么？帮忙翻译下这段C语言！

#include <stdio.h>
#include <stdlib.h>
 
#define SIZE 5000
 
char data[SIZE], code[SIZE]; 
int ptr, flag;
 
void interpreter(char *ip)
{
  char* re;
   
  while (*ip)
  {
  switch(*ip++)
  {
  case '<': --ptr; break;
  case '>': ++ptr; break;
  case '+': ++data[ptr]; break;
  case '-': --data[ptr]; break;
  case '.': putchar(data[ptr]); fflush(stdout); break;
  case ',': data[ptr] = getchar(); fflush(stdout); break;
  case '[': for (flag=1,re=ip; flag && *ip; ++ip)
  flag += *ip=='[', flag -= *ip==']';
  if(!flag)
  {
  ip[-1] = 0;
  while (data[ptr])
  interpreter(re);
  ip[-1] = ']';
  break;
  }
  case ']': puts("Unbalancded brackets!"), exit(-3);
  default : ;//SKIP
  }
  if (ptr < 0 || ptr > 100)
  puts("Out of Range"), exit(-4);
  }
}
  
int main(int argc, char *argv[])
{
  FILE *fin;
  int codelength;
   
  if (argc != 2)
  return puts("BrainFuck Interpreter v 0.1\nStar\nUsage:BFI filename"), 0;
  if ((fin = fopen(argv[1], "r")) == NULL)
  return puts("Cannot open file!"), -1;
  fseek(fin, 0, SEEK_END);
  if ((codelength = ftell(fin)) > SIZE)
  return puts("The program is too large."), -2;
  fseek(fin, 0, SEEK_SET);
  fread(code, codelength, 1, fin);
  code[codelength] = '\0';
  interpreter(code);
  return 0;
}

有些地方不太明白，有空的帮个忙吧，谢谢！

http://topic.csdn.net/u/20110611/01/2a3a79d0-37f1-475a-b9a9-0bab565fa73c.html?21365