#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>


MODULE_LICENSE("GPL");
MODULE_AUTHOR("wasabiz");

void run(const char* ipt)
{
  char dat[30000];
  int ptr = 0;
  int skr = 0;
  int brcn = 0;
  int i;
  char output[256];
  int len = 0;

  for(i=0;i<300;i++) dat[i] = 0;

  while (ipt[skr]!='\0') {
    //printf("%c\n", ipt[skr]);
    switch (ipt[skr]) {
    case '>':
      ptr++;
      break;
    case '<':
      ptr--;
      break;
    case '+':
      dat[ptr]--;
      break;
    case '-':
      dat[ptr]++;
      break;
    case '.':
      // Output dat[ptr]
      //      putchar(-dat[ptr]);
      output[len] = -dat[ptr];
      len++;
      break;
    case ',':
      // Input to dat[ptr]
      break;
    case '[':
      /* Jump to ] if dat[ptr] is 0 */
      if(!dat[ptr]){
        brcn = 0;
        while(1){
          skr++;
          if(ipt[skr] == '[') {
            brcn++;
          }else if(ipt[skr] == ']') {
            brcn--;
            if(!brcn) break;
          }
        }
        skr--;
      }
      break;
    case ']':
      /* Jump to [ if dat[ptr] is not 0 */
      if(dat[ptr]){
        brcn = 0;
        while(1){
          skr--;
          if(ipt[skr] == ']') {
            brcn++;
          }else if(ipt[skr] == '['){
            if(!brcn) break;
            brcn--;
          }
        }
        skr--;
      }
      break;
    }
    skr++;
  }

  output[len] = '\0';
  printk( KERN_INFO "%s", output);
}

static int
proc_write( struct file *flip, const char *buf, unsigned long len, void *data)
{
  char input_buf[1024];

  if (len >= 256) {
    printk( KERN_WARNING "proc_write len = %lu\n", len);
    return -ENOSPC;
  }

  if (copy_from_user(input_buf, buf, len)) return -EFAULT;
  input_buf[len] = '\0';

  run(input_buf);

  printk( KERN_INFO "proc_write %s\n", input_buf );
  return len;
}

static int
proc_read( char *page, char **start, off_t offset, int count, int *eof, void *data )
{
  int len;

  len = sprintf( page, "okok" );
  printk( KERN_INFO "proc_read len = %d\n", len );

  *eof = 1;
  return len;
}


#define PROCNAME "driver/brainfuck"

static int __init bfmod_init(void)
{
  struct proc_dir_entry *entry;

  entry = create_proc_entry( PROCNAME, 0666, NULL);
  if (entry) {
    entry->write_proc = proc_write;
    entry->read_proc = proc_read;
  } else {
    printk( KERN_ERR "create_proc_entry failed\n" );
    return -EBUSY;
  }

  printk( KERN_INFO "hoge mod is loaded\n" );

  return 0;
}

static void __exit bfmod_exit(void)
{
  remove_proc_entry( PROCNAME, NULL );
  printk( KERN_INFO "hoge exit hoge hoge" );
}

module_init(bfmod_init);
module_exit(bfmod_exit);