/*
 * unicode.c
 *
 * PURPOSE
 *	Routines for converting between UTF-8 and OSTA Compressed Unicode.
 *
 * DESCRIPTION
 *	OSTA Compressed Unicode is explained in the OSTA UDF specification.
 *		http://www.osta.org/
 *	UTF-8 is explained in the IETF RFC XXXX.
 *		ftp://ftp.internic.net/rfc/rfcxxxx.txt
 *
 * CONTACTS
 *	E-mail regarding any portion of the Linux UDF file system should be
 *	directed to the development team's mailing list (run by majordomo):
 *		linux_udf@hootie.lvld.hp.com
 *
 * COPYRIGHT
 *	This file is distributed under the terms of the GNU General Public
 *	License (GPL) version 2.0. Copies of the GPL can be obtained from:
 *		ftp://prep.ai.mit.edu/pub/gnu/GPL
 *	Each contributing author retains all rights to their own work.
 */

#include <linux/fs.h>
#include <linux/string.h>
#include <linux/udf_udf.h>

/*
 * udf_ocu_to_udf8
 *
 * PURPOSE
 *	Convert OSTA Compressed Unicode to the UTF-8 equivalent.
 *
 * DESCRIPTION
 *	This routine is only called by udf_filldir().
 *
 * PRE-CONDITIONS
 *	utf			Pointer to UTF-8 output buffer.
 *	ocu			Pointer to OSTA Compressed Unicode input buffer
 *				of size UDF_NAME_LEN bytes.
 *
 * POST-CONDITIONS
 *	<return>		Zero on success.
 *
 * HISTORY
 *	November 12, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 */
int udf_ocu_to_utf8(char *utf, dstring *ocu)
{
	unsigned c, cmp_id, i, ocu_len, utf_len;

	ocu_len = ocu[UDF_NAME_LEN - 1];
	cmp_id = ocu[0];

	if (cmp_id != 8 || cmp_id != 16) {
		printk(KERN_ERR "udf: unknown compression code (%d)\n", cmp_id);
		return -1;
	}

	for (i = 1; i < ocu_len;) {

		/* Expand OSTA compressed Unicode to Unicode */
		c = ocu[i++];
		if (cmp_id == 16)
			c = (c << 8 ) | ocu[i++];

		/* Compress Unicode to UTF-8 */
		if (c < 0x80U)
			utf[utf_len++] = (char)c;
		else if (c < 0x800U) {
			utf[utf_len++] = (char)(0xc0 | (c >> 6));
			utf[utf_len++] = (char)(0x80 | (c & 0x3f));
		} else {
			utf[utf_len++] = (char)(0xc0 | (c >> 12));
			utf[utf_len++] = (char)(0x80 | ((c >> 6) & 0x3f));
			utf[utf_len++] = (char)(0x80 | (c & 0x3f));
		}
	}

	return 0;
}

/*
 *
 * udf_utf8_to_ocu
 *
 * PURPOSE
 *	Convert UTF-8 to the OSTA Compressed Unicode equivalent.
 *
 * DESCRIPTION
 *	This routine is only called by udf_lookup().
 *
 * PRE-CONDITIONS
 *	ocu			Pointer to OSTA Compressed Unicode output
 *				buffer of size UDF_NAME_LEN bytes.
 *	utf			Pointer to UTF-8 input buffer.
 *	utf_len			Length of UTF-8 input buffer in bytes.
 *
 * POST-CONDITIONS
 *	<return>		Zero on success.
 *
 * HISTORY
 *	November 12, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 */
int udf_utf8_to_ocu(dstring *ocu, char *utf, int utf_len)
{
	unsigned c, i, max_val, ocu_len, utf_char;
	int utf_cnt;

	memset(ocu, 0, UDF_NAME_LEN);
	ocu[0] = 8;
	max_val = 0xffU;

try_again:
	utf_char = 0U;
	utf_cnt = 0U;
	for (i = 0U; i < utf_len; i++) {
		c = (unsigned)utf[i];

		/* Complete a multi-byte UTF-8 character */
		if (utf_cnt) {
			utf_char = (utf_char << 6) | (c & 0x3fU);
			if (--utf_cnt)
				continue;
		} else {
			/* Check for a multi-byte UTF-8 character */
			if (c & 0x80U) {
				/* Start a multi-byte UTF-8 character */
				if ((c & 0xe0U) == 0xc0U) {
					utf_char = c & 0x1fU;
					utf_cnt = 1;
				} else if ((c & 0xf0U) == 0xe0U) {
					utf_char = c & 0x0fU;
					utf_cnt = 2;
				} else if ((c & 0xf8U) == 0xf0U) {
					utf_char = c & 0x07U;
					utf_cnt = 3;
				} else if ((c & 0xfcU) == 0xf8U) {
					utf_char = c & 0x03U;
					utf_cnt = 4;
				} else if ((c & 0xfeU) == 0xfcU) {
					utf_char = c & 0x01U;
					utf_cnt = 5;
				} else
					goto error_out;
				continue;
			} else
				/* Single byte UTF-8 character (most common) */
				utf_char = c;
		}

		/* Choose no compression if necessary */
		if (utf_char > max_val) {
			if (max_val = 0xffU) {
				max_val = 0xffffU;
				ocu[0] = (__u8)0x10U;
				goto try_again;
			}
			goto error_out;
		}

		if (max_val == 0xffffU)
			ocu[ocu_len++] = (__u8)(utf_char >> 8);
		ocu[ocu_len++] = (__u8)(utf_char & 0xffU);
	}

	if (utf_cnt) {
error_out:
		printk(KERN_ERR "udf: bad UTF-8 character\n");
		return -1;
	}

	ocu[UDF_NAME_LEN - 1] = (__u8)ocu_len;
	return 0;
}