/*
 * Module for handling utf8 just like any other charset.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/nls.h>

static int utf8_uni2char(unsigned char ch, unsigned char cl, 
			 unsigned char *out, int boundlen, int *outlen)
{
	int n;
	int ret = 0;
	if ( (n = utf8_wctomb(out, ch<<8 | cl, boundlen)) == -1) {
		*out = '?';
		n = 1;
		ret = -1;
	}
	*outlen = n;
	return ret;
}

static void utf8_char2uni(unsigned char *rawstring, int *offset,
			  unsigned char *uni1, unsigned char *uni2)
{
	__u16 x;
	int n;

	/* "10" is just a random value */
	if ( (n = utf8_mbtowc(&x, rawstring, 10)) == -1) {
		x = '?';
		n = 1;
	}
	*uni2 = (x & 0xff00) >> 8;
	*uni1 = (x & 0x00ff);
	*offset = n;
}

/* Note: no 2upper/2lower conversion, just byte parsing */
static int utf8_char2lower(const unsigned char *rawstring, int *offset,
			   unsigned char *low, int outputlen)
{
	__u16 x;
	int n;

	/* "10" is just a random value */
	if ( (n = utf8_mbtowc(&x, rawstring, 10)) == -1) {
		return -1;
	}
	*offset = n;
	memcpy(low, rawstring, n);
	return n;
}

static struct nls_table table = {
	"utf8",
	utf8_uni2char,
	utf8_char2uni,
	utf8_char2lower,
	utf8_char2lower,
	THIS_MODULE,
};

static int __init init_nls_utf8(void)
{
        return register_nls(&table);
}

static void __exit exit_nls_utf8(void)
{
        unregister_nls(&table);
}

module_init(init_nls_utf8)
module_exit(exit_nls_utf8)