/*
 *  linux/fs/hfsplus/unicode.c
 *
 * Copyright (C) 2001
 * Brad Boyer (flar@allandria.com)
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 *
 * Handler routines for unicode strings
 */

#include <linux/types.h>
#include <linux/nls.h>
#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

/* Fold the case of a unicode char, given the 16 bit value */
/* Returns folded char, or 0 if ignorable */
static inline u16 case_fold(u16 c)
{
        u16 tmp;

        tmp = hfsplus_case_fold_table[c >> 8];
        if (tmp)
                tmp = hfsplus_case_fold_table[tmp + (c & 0xff)];
        else
                tmp = c;
        return tmp;
}

/* Compare unicode strings, return values like normal strcmp */
int hfsplus_unistrcmp(const struct hfsplus_unistr *s1, const struct hfsplus_unistr *s2)
{
	u16 len1, len2, c1, c2;
	const hfsplus_unichr *p1, *p2;

	len1 = be16_to_cpu(s1->length);
	len2 = be16_to_cpu(s2->length);
	p1 = s1->unicode;
	p2 = s2->unicode;

	while (1) {
		c1 = c2 = 0;

		while (len1 && !c1) {
			c1 = case_fold(be16_to_cpu(*p1));
			p1++;
			len1--;
		}
		while (len2 && !c2) {
			c2 = case_fold(be16_to_cpu(*p2));
			p2++;
			len2--;
		}

		if (c1 != c2)
			return (c1 < c2) ? -1 : 1;
		if (!c1 && !c2)
			return 0;
	}
}

#define Hangul_SBase	0xac00
#define Hangul_LBase	0x1100
#define Hangul_VBase	0x1161
#define Hangul_TBase	0x11a7
#define Hangul_SCount	11172
#define Hangul_LCount	19
#define Hangul_VCount	21
#define Hangul_TCount	28
#define Hangul_NCount	(Hangul_VCount * Hangul_TCount)


static u16 *hfsplus_compose_lookup(u16 *p, u16 cc)
{
	int i, s, e;

	s = 1;
	e = p[1];
	if (!e || cc < p[s * 2] || cc > p[e * 2])
		return NULL;
	do {
		i = (s + e) / 2;
		if (cc > p[i * 2])
			s = i + 1;
		else if (cc < p[i * 2])
			e = i - 1;
		else
			return hfsplus_compose_table + p[i * 2 + 1];
	} while (s <= e);
	return NULL;
}

int hfsplus_uni2asc(struct super_block *sb, const struct hfsplus_unistr *ustr, char *astr, int *len_p)
{
	const hfsplus_unichr *ip;
	struct nls_table *nls = HFSPLUS_SB(sb).nls;
	u8 *op;
	u16 cc, c0, c1;
	u16 *ce1, *ce2;
	int i, len, ustrlen, res, compose;

	op = astr;
	ip = ustr->unicode;
	ustrlen = be16_to_cpu(ustr->length);
	len = *len_p;
	ce1 = NULL;
	compose = !(HFSPLUS_SB(sb).flags & HFSPLUS_SB_NODECOMPOSE);

	while (ustrlen > 0) {
		c0 = be16_to_cpu(*ip++);
		ustrlen--;
		/* search for single decomposed char */
		if (likely(compose))
			ce1 = hfsplus_compose_lookup(hfsplus_compose_table, c0);
		if (ce1 && (cc = ce1[0])) {
			/* start of a possibly decomposed Hangul char */
			if (cc != 0xffff)
				goto done;
			if (!ustrlen)
				goto same;
			c1 = be16_to_cpu(*ip) - Hangul_VBase;
			if (c1 < Hangul_VCount) {
				/* compose the Hangul char */
				cc = (c0 - Hangul_LBase) * Hangul_VCount;
				cc = (cc + c1) * Hangul_TCount;
				cc += Hangul_SBase;
				ip++;
				ustrlen--;
				if (!ustrlen)
					goto done;
				c1 = be16_to_cpu(*ip) - Hangul_TBase;
				if (c1 > 0 && c1 < Hangul_TCount) {
					cc += c1;
					ip++;
					ustrlen--;
				}
				goto done;
			}
		}
		while (1) {
			/* main loop for common case of not composed chars */
			if (!ustrlen)
				goto same;
			c1 = be16_to_cpu(*ip);
			if (likely(compose))
				ce1 = hfsplus_compose_lookup(hfsplus_compose_table, c1);
			if (ce1)
				break;
			switch (c0) {
			case 0:
				c0 = 0x2400;
				break;
			case '/':
				c0 = ':';
				break;
			}
			res = nls->uni2char(c0, op, len);
			if (res < 0) {
				if (res == -ENAMETOOLONG)
					goto out;
				*op = '?';
				res = 1;
			}
			op += res;
			len -= res;
			c0 = c1;
			ip++;
			ustrlen--;
		}
		ce2 = hfsplus_compose_lookup(ce1, c0);
		if (ce2) {
			i = 1;
			while (i < ustrlen) {
				ce1 = hfsplus_compose_lookup(ce2, be16_to_cpu(ip[i]));
				if (!ce1)
					break;
				i++;
				ce2 = ce1;
			}
			if ((cc = ce2[0])) {
				ip += i;
				ustrlen -= i;
				goto done;
			}
		}
	same:
		switch (c0) {
		case 0:
			cc = 0x2400;
			break;
		case '/':
			cc = ':';
			break;
		default:
			cc = c0;
		}
	done:
		res = nls->uni2char(cc, op, len);
		if (res < 0) {
			if (res == -ENAMETOOLONG)
				goto out;
			*op = '?';
			res = 1;
		}
		op += res;
		len -= res;
	}
	res = 0;
out:
	*len_p = (char *)op - astr;
	return res;
}

int hfsplus_asc2uni(struct super_block *sb, struct hfsplus_unistr *ustr, const char *astr, int len)
{
	struct nls_table *nls = HFSPLUS_SB(sb).nls;
	int size, off, decompose;
	wchar_t c;
	u16 outlen = 0;

	decompose = !(HFSPLUS_SB(sb).flags & HFSPLUS_SB_NODECOMPOSE);

	while (outlen < HFSPLUS_MAX_STRLEN && len > 0) {
		size = nls->char2uni(astr, len, &c);
		if (size <= 0) {
			c = '?';
			size = 1;
		}
		astr += size;
		len -= size;
		switch (c) {
		case 0x2400:
			c = 0;
			break;
		case ':':
			c = '/';
			break;
		}
		if (c >= 0xc0 && decompose) {
			off = hfsplus_decompose_table[(c >> 12) & 0xf];
			if (!off)
				goto done;
			if (off == 0xffff) {
				goto done;
			}
			off = hfsplus_decompose_table[off + ((c >> 8) & 0xf)];
			if (!off)
				goto done;
			off = hfsplus_decompose_table[off + ((c >> 4) & 0xf)];
			if (!off)
				goto done;
			off = hfsplus_decompose_table[off + (c & 0xf)];
			size = off & 3;
			if (!size)
				goto done;
			off /= 4;
			if (outlen + size > HFSPLUS_MAX_STRLEN)
				break;
			do {
				ustr->unicode[outlen++] = cpu_to_be16(hfsplus_decompose_table[off++]);
			} while (--size > 0);
			continue;
		}
	done:
		ustr->unicode[outlen++] = cpu_to_be16(c);
	}
	ustr->length = cpu_to_be16(outlen);
	if (len > 0)
		return -ENAMETOOLONG;
	return 0;
}