/* 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 */