text: /*
   * linux/fs/nls/nls_koi8-ru.c
   *
   * Charset koi8-ru translation based on charset koi8-u.
   * The Unicode to charset table has only exact mappings.
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/nls.h>
  #include <linux/errno.h>
  
  static struct nls_table *p_nls;
  
  static int uni2char(const wchar_t uni,
  		    unsigned char *out, int boundlen)
  {
  	if (boundlen <= 0)
  		return -ENAMETOOLONG;
  
  	if ((uni & 0xffaf) == 0x040e || (uni & 0xffce) == 0x254c) {
  		/* koi8-ru and koi8-u differ only on two characters */
  		if (uni == 0x040e)
  			out[0] = 0xbe;
  		else if (uni == 0x045e)
  			out[0] = 0xae;
  		else if (uni == 0x255d || uni == 0x256c)
  			return 0;
  		else
  			return p_nls->uni2char(uni, out, boundlen);
  		return 1;
  	}
  	else
  		/* fast path */
  		return p_nls->uni2char(uni, out, boundlen);
  }
  
  static int char2uni(const unsigned char *rawstring, int boundlen,
  		    wchar_t *uni)
  {
  	int n;
  
  	if ((*rawstring & 0xef) != 0xae) {
  		/* koi8-ru and koi8-u differ only on two characters */
  		*uni = (*rawstring & 0x10) ? 0x040e : 0x045e;
  		return 1;
  	}
  
  	n = p_nls->char2uni(rawstring, boundlen, uni);
  	return n;
  }
  
  static struct nls_table table = {
  	.charset	= "koi8-ru",
  	.uni2char	= uni2char,
  	.char2uni	= char2uni,
  };
  
  static int __init init_nls_koi8_ru(void)
  {
  	p_nls = load_nls("koi8-u");
  
  	if (p_nls) {
  		table.charset2upper = p_nls->charset2upper;
  		table.charset2lower = p_nls->charset2lower;
  		return register_nls(&table);
  	}
  
  	return -EINVAL;
  }
  
  static void __exit exit_nls_koi8_ru(void)
  {
  	unregister_nls(&table);
  	unload_nls(p_nls);
  }
  
  module_init(init_nls_koi8_ru)
  module_exit(exit_nls_koi8_ru)
  
  MODULE_LICENSE("Dual BSD/GPL");
  