/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Some of the source code in this file came from fs/cifs/cifs_unicode.c
 * and then via server/unicode.c
 * cifs_unicode:  Unicode kernel case support
 *
 * Function:
 *     Convert a unicode character to upper or lower case using
 *     compressed tables.
 *
 *   Copyright (c) International Business Machines  Corp., 2000,2009
 *
 *
 * Notes:
 *     These APIs are based on the C library functions.  The semantics
 *     should match the C functions but with expanded size operands.
 *
 *     The upper/lower functions are based on a table created by mkupr.
 *     This is a compressed table of upper and lower case conversion.
 *
 */
#ifndef _NLS_UCS2_UTILS_H
#define _NLS_UCS2_UTILS_H

#include <asm/byteorder.h>
#include <linux/types.h>
#include <linux/nls.h>
#include <linux/unicode.h>
#include "nls_ucs2_data.h"

/*
 * Windows maps these to the user defined 16 bit Unicode range since they are
 * reserved symbols (along with \ and /), otherwise illegal to store
 * in filenames in NTFS
 */
#define UNI_ASTERISK    ((__u16)('*' + 0xF000))
#define UNI_QUESTION    ((__u16)('?' + 0xF000))
#define UNI_COLON       ((__u16)(':' + 0xF000))
#define UNI_GRTRTHAN    ((__u16)('>' + 0xF000))
#define UNI_LESSTHAN    ((__u16)('<' + 0xF000))
#define UNI_PIPE        ((__u16)('|' + 0xF000))
#define UNI_SLASH       ((__u16)('\\' + 0xF000))

/*
 * UniStrcat:  Concatenate the second string to the first
 *
 * Returns:
 *     Address of the first string
 */
static inline wchar_t *UniStrcat(wchar_t *ucs1, const wchar_t *ucs2)
{
	wchar_t *anchor = ucs1;	/* save a pointer to start of ucs1 */

	while (*ucs1++)
	/*NULL*/;	/* To end of first string */
	ucs1--;			/* Return to the null */
	while ((*ucs1++ = *ucs2++))
	/*NULL*/;	/* copy string 2 over */
	return anchor;
}

/*
 * UniStrchr:  Find a character in a string
 *
 * Returns:
 *     Address of first occurrence of character in string
 *     or NULL if the character is not in the string
 */
static inline wchar_t *UniStrchr(const wchar_t *ucs, wchar_t uc)
{
	while ((*ucs != uc) && *ucs)
		ucs++;

	if (*ucs == uc)
		return (wchar_t *)ucs;
	return NULL;
}

/*
 * UniStrcmp:  Compare two strings
 *
 * Returns:
 *     < 0:  First string is less than second
 *     = 0:  Strings are equal
 *     > 0:  First string is greater than second
 */
static inline int UniStrcmp(const wchar_t *ucs1, const wchar_t *ucs2)
{
	while ((*ucs1 == *ucs2) && *ucs1) {
		ucs1++;
		ucs2++;
	}
	return (int)*ucs1 - (int)*ucs2;
}

/*
 * UniStrcpy:  Copy a string
 */
static inline wchar_t *UniStrcpy(wchar_t *ucs1, const wchar_t *ucs2)
{
	wchar_t *anchor = ucs1;	/* save the start of result string */

	while ((*ucs1++ = *ucs2++))
	/*NULL*/;
	return anchor;
}

/*
 * UniStrlen:  Return the length of a string (in 16 bit Unicode chars not bytes)
 */
static inline size_t UniStrlen(const wchar_t *ucs1)
{
	int i = 0;

	while (*ucs1++)
		i++;
	return i;
}

/*
 * UniStrnlen:  Return the length (in 16 bit Unicode chars not bytes) of a
 *		string (length limited)
 */
static inline size_t UniStrnlen(const wchar_t *ucs1, int maxlen)
{
	int i = 0;

	while (*ucs1++) {
		i++;
		if (i >= maxlen)
			break;
	}
	return i;
}

/*
 * UniStrncat:  Concatenate length limited string
 */
static inline wchar_t *UniStrncat(wchar_t *ucs1, const wchar_t *ucs2, size_t n)
{
	wchar_t *anchor = ucs1;	/* save pointer to string 1 */

	while (*ucs1++)
	/*NULL*/;
	ucs1--;			/* point to null terminator of s1 */
	while (n-- && (*ucs1 = *ucs2)) {	/* copy s2 after s1 */
		ucs1++;
		ucs2++;
	}
	*ucs1 = 0;		/* Null terminate the result */
	return anchor;
}

/*
 * UniStrncmp:  Compare length limited string
 */
static inline int UniStrncmp(const wchar_t *ucs1, const wchar_t *ucs2, size_t n)
{
	if (!n)
		return 0;	/* Null strings are equal */
	while ((*ucs1 == *ucs2) && *ucs1 && --n) {
		ucs1++;
		ucs2++;
	}
	return (int)*ucs1 - (int)*ucs2;
}

/*
 * UniStrncmp_le:  Compare length limited string - native to little-endian
 */
static inline int
UniStrncmp_le(const wchar_t *ucs1, const wchar_t *ucs2, size_t n)
{
	if (!n)
		return 0;	/* Null strings are equal */
	while ((*ucs1 == __le16_to_cpu(*ucs2)) && *ucs1 && --n) {
		ucs1++;
		ucs2++;
	}
	return (int)*ucs1 - (int)__le16_to_cpu(*ucs2);
}

/*
 * UniStrncpy:  Copy length limited string with pad
 */
static inline wchar_t *UniStrncpy(wchar_t *ucs1, const wchar_t *ucs2, size_t n)
{
	wchar_t *anchor = ucs1;

	while (n-- && *ucs2)	/* Copy the strings */
		*ucs1++ = *ucs2++;

	n++;
	while (n--)		/* Pad with nulls */
		*ucs1++ = 0;
	return anchor;
}

/*
 * UniStrncpy_le:  Copy length limited string with pad to little-endian
 */
static inline wchar_t *UniStrncpy_le(wchar_t *ucs1, const wchar_t *ucs2, size_t n)
{
	wchar_t *anchor = ucs1;

	while (n-- && *ucs2)	/* Copy the strings */
		*ucs1++ = __le16_to_cpu(*ucs2++);

	n++;
	while (n--)		/* Pad with nulls */
		*ucs1++ = 0;
	return anchor;
}

/*
 * UniStrstr:  Find a string in a string
 *
 * Returns:
 *     Address of first match found
 *     NULL if no matching string is found
 */
static inline wchar_t *UniStrstr(const wchar_t *ucs1, const wchar_t *ucs2)
{
	const wchar_t *anchor1 = ucs1;
	const wchar_t *anchor2 = ucs2;

	while (*ucs1) {
		if (*ucs1 == *ucs2) {
			/* Partial match found */
			ucs1++;
			ucs2++;
		} else {
			if (!*ucs2)	/* Match found */
				return (wchar_t *)anchor1;
			ucs1 = ++anchor1;	/* No match */
			ucs2 = anchor2;
		}
	}

	if (!*ucs2)		/* Both end together */
		return (wchar_t *)anchor1;	/* Match found */
	return NULL;		/* No match */
}

#ifndef UNIUPR_NOUPPER
/*
 * UniToupper:  Convert a unicode character to upper case
 */
static inline wchar_t UniToupper(register wchar_t uc)
{
	register const struct UniCaseRange *rp;

	if (uc < sizeof(NlsUniUpperTable)) {
		/* Latin characters */
		return uc + NlsUniUpperTable[uc];	/* Use base tables */
	}

	rp = NlsUniUpperRange;	/* Use range tables */
	while (rp->start) {
		if (uc < rp->start)	/* Before start of range */
			return uc;	/* Uppercase = input */
		if (uc <= rp->end)	/* In range */
			return uc + rp->table[uc - rp->start];
		rp++;	/* Try next range */
	}
	return uc;		/* Past last range */
}

/*
 * UniStrupr:  Upper case a unicode string
 */
static inline __le16 *UniStrupr(register __le16 *upin)
{
	register __le16 *up;

	up = upin;
	while (*up) {		/* For all characters */
		*up = cpu_to_le16(UniToupper(le16_to_cpu(*up)));
		up++;
	}
	return upin;		/* Return input pointer */
}
#endif				/* UNIUPR_NOUPPER */

#endif /* _NLS_UCS2_UTILS_H */