/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Unicode encoding conversion functions among UTF-8, UTF-16, and UTF-32.
 * (PSARC/2005/446, PSARC/2007/038, PSARC/2007/517)
 * Man pages: uconv_u16tou32(9F), uconv_u16tou8(9F), uconv_u32tou16(9F),
 * uconv_u32tou8(9F), uconv_u8tou16(9F), and uconv_u8tou32(9F). See also
 * the section 3C man pages.
 * Interface stability: Committed
 */

#include <sys/types.h>
#ifdef  _KERNEL
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/debug.h>
#include <sys/kmem.h>
#include <sys/sunddi.h>
#else
#include <sys/u8_textprep.h>
#endif  /* _KERNEL */
#include <sys/byteorder.h>
#include <sys/errno.h>


/*
 * The max and min values of high and low surrogate pairs of UTF-16,
 * UTF-16 bit shift value, bit mask, and starting value outside of BMP.
 */
#define UCONV_U16_HI_MIN        (0xd800U)
#define UCONV_U16_HI_MAX        (0xdbffU)
#define UCONV_U16_LO_MIN        (0xdc00U)
#define UCONV_U16_LO_MAX        (0xdfffU)
#define UCONV_U16_BIT_SHIFT     (0x0400U)
#define UCONV_U16_BIT_MASK      (0x0fffffU)
#define UCONV_U16_START         (0x010000U)

/* The maximum value of Unicode coding space and ASCII coding space. */
#define UCONV_UNICODE_MAX       (0x10ffffU)
#define UCONV_ASCII_MAX         (0x7fU)

/* The mask values for input and output endians. */
#define UCONV_IN_ENDIAN_MASKS   (UCONV_IN_BIG_ENDIAN | UCONV_IN_LITTLE_ENDIAN)
#define UCONV_OUT_ENDIAN_MASKS  (UCONV_OUT_BIG_ENDIAN | UCONV_OUT_LITTLE_ENDIAN)

/* Native and reversed endian macros. */
#ifdef  _BIG_ENDIAN
#define UCONV_IN_NAT_ENDIAN     UCONV_IN_BIG_ENDIAN
#define UCONV_IN_REV_ENDIAN     UCONV_IN_LITTLE_ENDIAN
#define UCONV_OUT_NAT_ENDIAN    UCONV_OUT_BIG_ENDIAN
#define UCONV_OUT_REV_ENDIAN    UCONV_OUT_LITTLE_ENDIAN
#else
#define UCONV_IN_NAT_ENDIAN     UCONV_IN_LITTLE_ENDIAN
#define UCONV_IN_REV_ENDIAN     UCONV_IN_BIG_ENDIAN
#define UCONV_OUT_NAT_ENDIAN    UCONV_OUT_LITTLE_ENDIAN
#define UCONV_OUT_REV_ENDIAN    UCONV_OUT_BIG_ENDIAN
#endif  /* _BIG_ENDIAN */

/* The Byte Order Mark (BOM) character in normal and reversed byte orderings. */
#define UCONV_BOM_NORMAL        (0xfeffU)
#define UCONV_BOM_SWAPPED       (0xfffeU)
#define UCONV_BOM_SWAPPED_32    (0xfffe0000U)

/* UTF-32 boundaries based on UTF-8 character byte lengths. */
#define UCONV_U8_ONE_BYTE       (0x7fU)
#define UCONV_U8_TWO_BYTES      (0x7ffU)
#define UCONV_U8_THREE_BYTES    (0xffffU)
#define UCONV_U8_FOUR_BYTES     (0x10ffffU)

/* The common minimum and maximum values at the UTF-8 character bytes. */
#define UCONV_U8_BYTE_MIN       (0x80U)
#define UCONV_U8_BYTE_MAX       (0xbfU)

/*
 * The following "6" and "0x3f" came from "10xx xxxx" bit representation of
 * UTF-8 character bytes.
 */
#define UCONV_U8_BIT_SHIFT      6
#define UCONV_U8_BIT_MASK       0x3f

/*
 * The following vector shows remaining bytes in a UTF-8 character.
 * Index will be the first byte of the character.
 */
static const uchar_t remaining_bytes_tbl[0x100] = {
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
        0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,

/*      C0  C1  C2  C3  C4  C5  C6  C7  C8  C9  CA  CB  CC  CD  CE  CF */
        0,  0,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,

/*      D0  D1  D2  D3  D4  D5  D6  D7  D8  D9  DA  DB  DC  DD  DE  DF */
        1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,

/*      E0  E1  E2  E3  E4  E5  E6  E7  E8  E9  EA  EB  EC  ED  EE  EF */
        2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,

/*      F0  F1  F2  F3  F4  F5  F6  F7  F8  F9  FA  FB  FC  FD  FE  FF */
        3,  3,  3,  3,  3,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0
};

/*
 * The following is a vector of bit-masks to get used bits in
 * the first byte of a UTF-8 character.  Index is remaining bytes at above of
 * the character.
 */
#ifdef  _KERNEL
const uchar_t u8_masks_tbl[6] = { 0x00, 0x1f, 0x0f, 0x07, 0x03, 0x01 };
#else
static const uchar_t u8_masks_tbl[6] = { 0x00, 0x1f, 0x0f, 0x07, 0x03, 0x01 };
#endif  /* _KERNEL */

/*
 * The following two vectors are to provide valid minimum and
 * maximum values for the 2'nd byte of a multibyte UTF-8 character for
 * better illegal sequence checking. The index value must be the value of
 * the first byte of the UTF-8 character.
 */
static const uchar_t valid_min_2nd_byte[0x100] = {
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,

/*      C0    C1    C2    C3    C4    C5    C6    C7 */
        0,    0,    0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

/*      C8    C9    CA    CB    CC    CD    CE    CF */
        0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

/*      D0    D1    D2    D3    D4    D5    D6    D7 */
        0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

/*      D8    D9    DA    DB    DC    DD    DE    DF */
        0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

/*      E0    E1    E2    E3    E4    E5    E6    E7 */
        0xa0, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

/*      E8    E9    EA    EB    EC    ED    EE    EF */
        0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,

/*      F0    F1    F2    F3    F4    F5    F6    F7 */
        0x90, 0x80, 0x80, 0x80, 0x80, 0,    0,    0,

        0,    0,    0,    0,    0,    0,    0,    0
};

static const uchar_t valid_max_2nd_byte[0x100] = {
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,
        0,    0,    0,    0,    0,    0,    0,    0,

/*      C0    C1    C2    C3    C4    C5    C6    C7 */
        0,    0,    0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,

/*      C8    C9    CA    CB    CC    CD    CE    CF */
        0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,

/*      D0    D1    D2    D3    D4    D5    D6    D7 */
        0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,

/*      D8    D9    DA    DB    DC    DD    DE    DF */
        0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,

/*      E0    E1    E2    E3    E4    E5    E6    E7 */
        0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0xbf,

/*      E8    E9    EA    EB    EC    ED    EE    EF */
        0xbf, 0xbf, 0xbf, 0xbf, 0xbf, 0x9f, 0xbf, 0xbf,

/*      F0    F1    F2    F3    F4    F5    F6    F7 */
        0xbf, 0xbf, 0xbf, 0xbf, 0x8f, 0,    0,    0,

        0,    0,    0,    0,    0,    0,    0,    0
};


static int
check_endian(int flag, int *in, int *out)
{
        *in = flag & UCONV_IN_ENDIAN_MASKS;

        /* You cannot have both. */
        if (*in == UCONV_IN_ENDIAN_MASKS)
                return (EBADF);

        if (*in == 0)
                *in = UCONV_IN_NAT_ENDIAN;

        *out = flag & UCONV_OUT_ENDIAN_MASKS;

        /* You cannot have both. */
        if (*out == UCONV_OUT_ENDIAN_MASKS)
                return (EBADF);

        if (*out == 0)
                *out = UCONV_OUT_NAT_ENDIAN;

        return (0);
}

static boolean_t
check_bom16(const uint16_t *u16s, size_t u16l, int *in)
{
        if (u16l > 0) {
                if (*u16s == UCONV_BOM_NORMAL) {
                        *in = UCONV_IN_NAT_ENDIAN;
                        return (B_TRUE);
                }
                if (*u16s == UCONV_BOM_SWAPPED) {
                        *in = UCONV_IN_REV_ENDIAN;
                        return (B_TRUE);
                }
        }

        return (B_FALSE);
}

static boolean_t
check_bom32(const uint32_t *u32s, size_t u32l, int *in)
{
        if (u32l > 0) {
                if (*u32s == UCONV_BOM_NORMAL) {
                        *in = UCONV_IN_NAT_ENDIAN;
                        return (B_TRUE);
                }
                if (*u32s == UCONV_BOM_SWAPPED_32) {
                        *in = UCONV_IN_REV_ENDIAN;
                        return (B_TRUE);
                }
        }

        return (B_FALSE);
}

int
uconv_u16tou32(const uint16_t *u16s, size_t *utf16len,
    uint32_t *u32s, size_t *utf32len, int flag)
{
        int inendian;
        int outendian;
        size_t u16l;
        size_t u32l;
        uint32_t hi;
        uint32_t lo;
        boolean_t do_not_ignore_null;

        /*
         * Do preliminary validity checks on parameters and collect info on
         * endians.
         */
        if (u16s == NULL || utf16len == NULL)
                return (EILSEQ);

        if (u32s == NULL || utf32len == NULL)
                return (E2BIG);

        if (check_endian(flag, &inendian, &outendian) != 0)
                return (EBADF);

        /*
         * Initialize input and output parameter buffer indices and
         * temporary variables.
         */
        u16l = u32l = 0;
        hi = 0;
        do_not_ignore_null = ((flag & UCONV_IGNORE_NULL) == 0);

        /*
         * Check on the BOM at the beginning of the input buffer if required
         * and if there is indeed one, process it.
         */
        if ((flag & UCONV_IN_ACCEPT_BOM) &&
            check_bom16(u16s, *utf16len, &inendian))
                u16l++;

        /*
         * Reset inendian and outendian so that after this point, those can be
         * used as condition values.
         */
        inendian &= UCONV_IN_NAT_ENDIAN;
        outendian &= UCONV_OUT_NAT_ENDIAN;

        /*
         * If there is something in the input buffer and if necessary and
         * requested, save the BOM at the output buffer.
         */
        if (*utf16len > 0 && *utf32len > 0 && (flag & UCONV_OUT_EMIT_BOM))
                u32s[u32l++] = (outendian) ? UCONV_BOM_NORMAL :
                    UCONV_BOM_SWAPPED_32;

        /*
         * Do conversion; if encounter a surrogate pair, assemble high and
         * low pair values to form a UTF-32 character. If a half of a pair
         * exists alone, then, either it is an illegal (EILSEQ) or
         * invalid (EINVAL) value.
         */
        for (; u16l < *utf16len; u16l++) {
                if (u16s[u16l] == 0 && do_not_ignore_null)
                        break;

                lo = (uint32_t)((inendian) ? u16s[u16l] : BSWAP_16(u16s[u16l]));

                if (lo >= UCONV_U16_HI_MIN && lo <= UCONV_U16_HI_MAX) {
                        if (hi)
                                return (EILSEQ);
                        hi = lo;
                        continue;
                } else if (lo >= UCONV_U16_LO_MIN && lo <= UCONV_U16_LO_MAX) {
                        if (! hi)
                                return (EILSEQ);
                        lo = (((hi - UCONV_U16_HI_MIN) * UCONV_U16_BIT_SHIFT +
                            lo - UCONV_U16_LO_MIN) & UCONV_U16_BIT_MASK)
                            + UCONV_U16_START;
                        hi = 0;
                } else if (hi) {
                        return (EILSEQ);
                }

                if (u32l >= *utf32len)
                        return (E2BIG);

                u32s[u32l++] = (outendian) ? lo : BSWAP_32(lo);
        }

        /*
         * If high half didn't see low half, then, it's most likely the input
         * parameter is incomplete.
         */
        if (hi)
                return (EINVAL);

        /*
         * Save the number of consumed and saved characters. They do not
         * include terminating NULL character (U+0000) at the end of
         * the input buffer (even when UCONV_IGNORE_NULL isn't specified and
         * the input buffer length is big enough to include the terminating
         * NULL character).
         */
        *utf16len = u16l;
        *utf32len = u32l;

        return (0);
}

int
uconv_u16tou8(const uint16_t *u16s, size_t *utf16len,
    uchar_t *u8s, size_t *utf8len, int flag)
{
        int inendian;
        int outendian;
        size_t u16l;
        size_t u8l;
        uint32_t hi;
        uint32_t lo;
        boolean_t do_not_ignore_null;

        if (u16s == NULL || utf16len == NULL)
                return (EILSEQ);

        if (u8s == NULL || utf8len == NULL)
                return (E2BIG);

        if (check_endian(flag, &inendian, &outendian) != 0)
                return (EBADF);

        u16l = u8l = 0;
        hi = 0;
        do_not_ignore_null = ((flag & UCONV_IGNORE_NULL) == 0);

        if ((flag & UCONV_IN_ACCEPT_BOM) &&
            check_bom16(u16s, *utf16len, &inendian))
                u16l++;

        inendian &= UCONV_IN_NAT_ENDIAN;

        for (; u16l < *utf16len; u16l++) {
                if (u16s[u16l] == 0 && do_not_ignore_null)
                        break;

                lo = (uint32_t)((inendian) ? u16s[u16l] : BSWAP_16(u16s[u16l]));

                if (lo >= UCONV_U16_HI_MIN && lo <= UCONV_U16_HI_MAX) {
                        if (hi)
                                return (EILSEQ);
                        hi = lo;
                        continue;
                } else if (lo >= UCONV_U16_LO_MIN && lo <= UCONV_U16_LO_MAX) {
                        if (! hi)
                                return (EILSEQ);
                        lo = (((hi - UCONV_U16_HI_MIN) * UCONV_U16_BIT_SHIFT +
                            lo - UCONV_U16_LO_MIN) & UCONV_U16_BIT_MASK)
                            + UCONV_U16_START;
                        hi = 0;
                } else if (hi) {
                        return (EILSEQ);
                }

                /*
                 * Now we convert a UTF-32 character into a UTF-8 character.
                 * Unicode coding space is between U+0000 and U+10FFFF;
                 * anything bigger is an illegal character.
                 */
                if (lo <= UCONV_U8_ONE_BYTE) {
                        if (u8l >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)lo;
                } else if (lo <= UCONV_U8_TWO_BYTES) {
                        if ((u8l + 1) >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)(0xc0 | ((lo & 0x07c0) >> 6));
                        u8s[u8l++] = (uchar_t)(0x80 |  (lo & 0x003f));
                } else if (lo <= UCONV_U8_THREE_BYTES) {
                        if ((u8l + 2) >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)(0xe0 | ((lo & 0x0f000) >> 12));
                        u8s[u8l++] = (uchar_t)(0x80 | ((lo & 0x00fc0) >> 6));
                        u8s[u8l++] = (uchar_t)(0x80 |  (lo & 0x0003f));
                } else if (lo <= UCONV_U8_FOUR_BYTES) {
                        if ((u8l + 3) >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)(0xf0 | ((lo & 0x01c0000) >> 18));
                        u8s[u8l++] = (uchar_t)(0x80 | ((lo & 0x003f000) >> 12));
                        u8s[u8l++] = (uchar_t)(0x80 | ((lo & 0x0000fc0) >> 6));
                        u8s[u8l++] = (uchar_t)(0x80 |  (lo & 0x000003f));
                } else {
                        return (EILSEQ);
                }
        }

        if (hi)
                return (EINVAL);

        *utf16len = u16l;
        *utf8len = u8l;

        return (0);
}

int
uconv_u32tou16(const uint32_t *u32s, size_t *utf32len,
    uint16_t *u16s, size_t *utf16len, int flag)
{
        int inendian;
        int outendian;
        size_t u16l;
        size_t u32l;
        uint32_t hi;
        uint32_t lo;
        boolean_t do_not_ignore_null;

        if (u32s == NULL || utf32len == NULL)
                return (EILSEQ);

        if (u16s == NULL || utf16len == NULL)
                return (E2BIG);

        if (check_endian(flag, &inendian, &outendian) != 0)
                return (EBADF);

        u16l = u32l = 0;
        do_not_ignore_null = ((flag & UCONV_IGNORE_NULL) == 0);

        if ((flag & UCONV_IN_ACCEPT_BOM) &&
            check_bom32(u32s, *utf32len, &inendian))
                u32l++;

        inendian &= UCONV_IN_NAT_ENDIAN;
        outendian &= UCONV_OUT_NAT_ENDIAN;

        if (*utf32len > 0 && *utf16len > 0 && (flag & UCONV_OUT_EMIT_BOM))
                u16s[u16l++] = (outendian) ? UCONV_BOM_NORMAL :
                    UCONV_BOM_SWAPPED;

        for (; u32l < *utf32len; u32l++) {
                if (u32s[u32l] == 0 && do_not_ignore_null)
                        break;

                hi = (inendian) ? u32s[u32l] : BSWAP_32(u32s[u32l]);

                /*
                 * Anything bigger than the Unicode coding space, i.e.,
                 * Unicode scalar value bigger than U+10FFFF, is an illegal
                 * character.
                 */
                if (hi > UCONV_UNICODE_MAX)
                        return (EILSEQ);

                /*
                 * Anything bigger than U+FFFF must be converted into
                 * a surrogate pair in UTF-16.
                 */
                if (hi >= UCONV_U16_START) {
                        lo = ((hi - UCONV_U16_START) % UCONV_U16_BIT_SHIFT) +
                            UCONV_U16_LO_MIN;
                        hi = ((hi - UCONV_U16_START) / UCONV_U16_BIT_SHIFT) +
                            UCONV_U16_HI_MIN;

                        if ((u16l + 1) >= *utf16len)
                                return (E2BIG);

                        if (outendian) {
                                u16s[u16l++] = (uint16_t)hi;
                                u16s[u16l++] = (uint16_t)lo;
                        } else {
                                u16s[u16l++] = BSWAP_16(((uint16_t)hi));
                                u16s[u16l++] = BSWAP_16(((uint16_t)lo));
                        }
                } else {
                        if (u16l >= *utf16len)
                                return (E2BIG);
                        u16s[u16l++] = (outendian) ? (uint16_t)hi :
                            BSWAP_16(((uint16_t)hi));
                }
        }

        *utf16len = u16l;
        *utf32len = u32l;

        return (0);
}

int
uconv_u32tou8(const uint32_t *u32s, size_t *utf32len,
    uchar_t *u8s, size_t *utf8len, int flag)
{
        int inendian;
        int outendian;
        size_t u32l;
        size_t u8l;
        uint32_t lo;
        boolean_t do_not_ignore_null;

        if (u32s == NULL || utf32len == NULL)
                return (EILSEQ);

        if (u8s == NULL || utf8len == NULL)
                return (E2BIG);

        if (check_endian(flag, &inendian, &outendian) != 0)
                return (EBADF);

        u32l = u8l = 0;
        do_not_ignore_null = ((flag & UCONV_IGNORE_NULL) == 0);

        if ((flag & UCONV_IN_ACCEPT_BOM) &&
            check_bom32(u32s, *utf32len, &inendian))
                u32l++;

        inendian &= UCONV_IN_NAT_ENDIAN;

        for (; u32l < *utf32len; u32l++) {
                if (u32s[u32l] == 0 && do_not_ignore_null)
                        break;

                lo = (inendian) ? u32s[u32l] : BSWAP_32(u32s[u32l]);

                if (lo <= UCONV_U8_ONE_BYTE) {
                        if (u8l >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)lo;
                } else if (lo <= UCONV_U8_TWO_BYTES) {
                        if ((u8l + 1) >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)(0xc0 | ((lo & 0x07c0) >> 6));
                        u8s[u8l++] = (uchar_t)(0x80 |  (lo & 0x003f));
                } else if (lo <= UCONV_U8_THREE_BYTES) {
                        if ((u8l + 2) >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)(0xe0 | ((lo & 0x0f000) >> 12));
                        u8s[u8l++] = (uchar_t)(0x80 | ((lo & 0x00fc0) >> 6));
                        u8s[u8l++] = (uchar_t)(0x80 |  (lo & 0x0003f));
                } else if (lo <= UCONV_U8_FOUR_BYTES) {
                        if ((u8l + 3) >= *utf8len)
                                return (E2BIG);
                        u8s[u8l++] = (uchar_t)(0xf0 | ((lo & 0x01c0000) >> 18));
                        u8s[u8l++] = (uchar_t)(0x80 | ((lo & 0x003f000) >> 12));
                        u8s[u8l++] = (uchar_t)(0x80 | ((lo & 0x0000fc0) >> 6));
                        u8s[u8l++] = (uchar_t)(0x80 |  (lo & 0x000003f));
                } else {
                        return (EILSEQ);
                }
        }

        *utf32len = u32l;
        *utf8len = u8l;

        return (0);
}

int
uconv_u8tou16(const uchar_t *u8s, size_t *utf8len,
    uint16_t *u16s, size_t *utf16len, int flag)
{
        int inendian;
        int outendian;
        size_t u16l;
        size_t u8l;
        uint32_t hi;
        uint32_t lo;
        int remaining_bytes;
        int first_b;
        boolean_t do_not_ignore_null;

        if (u8s == NULL || utf8len == NULL)
                return (EILSEQ);

        if (u16s == NULL || utf16len == NULL)
                return (E2BIG);

        if (check_endian(flag, &inendian, &outendian) != 0)
                return (EBADF);

        u16l = u8l = 0;
        do_not_ignore_null = ((flag & UCONV_IGNORE_NULL) == 0);

        outendian &= UCONV_OUT_NAT_ENDIAN;

        if (*utf8len > 0 && *utf16len > 0 && (flag & UCONV_OUT_EMIT_BOM))
                u16s[u16l++] = (outendian) ? UCONV_BOM_NORMAL :
                    UCONV_BOM_SWAPPED;

        for (; u8l < *utf8len; ) {
                if (u8s[u8l] == 0 && do_not_ignore_null)
                        break;

                /*
                 * Collect a UTF-8 character and convert it to a UTF-32
                 * character. In doing so, we screen out illegally formed
                 * UTF-8 characters and treat such as illegal characters.
                 * The algorithm at below also screens out anything bigger
                 * than the U+10FFFF.
                 *
                 * See Unicode 3.1 UTF-8 Corrigendum and Unicode 3.2 for
                 * more details on the illegal values of UTF-8 character
                 * bytes.
                 */
                hi = (uint32_t)u8s[u8l++];

                if (hi > UCONV_ASCII_MAX) {
                        if ((remaining_bytes = remaining_bytes_tbl[hi]) == 0)
                                return (EILSEQ);

                        first_b = hi;
                        hi = hi & u8_masks_tbl[remaining_bytes];

                        for (; remaining_bytes > 0; remaining_bytes--) {
                                /*
                                 * If we have no more bytes, the current
                                 * UTF-8 character is incomplete.
                                 */
                                if (u8l >= *utf8len)
                                        return (EINVAL);

                                lo = (uint32_t)u8s[u8l++];

                                if (first_b) {
                                        if (lo < valid_min_2nd_byte[first_b] ||
                                            lo > valid_max_2nd_byte[first_b])
                                                return (EILSEQ);
                                        first_b = 0;
                                } else if (lo < UCONV_U8_BYTE_MIN ||
                                    lo > UCONV_U8_BYTE_MAX) {
                                        return (EILSEQ);
                                }
                                hi = (hi << UCONV_U8_BIT_SHIFT) |
                                    (lo & UCONV_U8_BIT_MASK);
                        }
                }

                if (hi >= UCONV_U16_START) {
                        lo = ((hi - UCONV_U16_START) % UCONV_U16_BIT_SHIFT) +
                            UCONV_U16_LO_MIN;
                        hi = ((hi - UCONV_U16_START) / UCONV_U16_BIT_SHIFT) +
                            UCONV_U16_HI_MIN;

                        if ((u16l + 1) >= *utf16len)
                                return (E2BIG);

                        if (outendian) {
                                u16s[u16l++] = (uint16_t)hi;
                                u16s[u16l++] = (uint16_t)lo;
                        } else {
                                u16s[u16l++] = BSWAP_16(((uint16_t)hi));
                                u16s[u16l++] = BSWAP_16(((uint16_t)lo));
                        }
                } else {
                        if (u16l >= *utf16len)
                                return (E2BIG);

                        u16s[u16l++] = (outendian) ? (uint16_t)hi :
                            BSWAP_16(((uint16_t)hi));
                }
        }

        *utf16len = u16l;
        *utf8len = u8l;

        return (0);
}

int
uconv_u8tou32(const uchar_t *u8s, size_t *utf8len,
    uint32_t *u32s, size_t *utf32len, int flag)
{
        int inendian;
        int outendian;
        size_t u32l;
        size_t u8l;
        uint32_t hi;
        uint32_t c;
        int remaining_bytes;
        int first_b;
        boolean_t do_not_ignore_null;

        if (u8s == NULL || utf8len == NULL)
                return (EILSEQ);

        if (u32s == NULL || utf32len == NULL)
                return (E2BIG);

        if (check_endian(flag, &inendian, &outendian) != 0)
                return (EBADF);

        u32l = u8l = 0;
        do_not_ignore_null = ((flag & UCONV_IGNORE_NULL) == 0);

        outendian &= UCONV_OUT_NAT_ENDIAN;

        if (*utf8len > 0 && *utf32len > 0 && (flag & UCONV_OUT_EMIT_BOM))
                u32s[u32l++] = (outendian) ? UCONV_BOM_NORMAL :
                    UCONV_BOM_SWAPPED_32;

        for (; u8l < *utf8len; ) {
                if (u8s[u8l] == 0 && do_not_ignore_null)
                        break;

                hi = (uint32_t)u8s[u8l++];

                if (hi > UCONV_ASCII_MAX) {
                        if ((remaining_bytes = remaining_bytes_tbl[hi]) == 0)
                                return (EILSEQ);

                        first_b = hi;
                        hi = hi & u8_masks_tbl[remaining_bytes];

                        for (; remaining_bytes > 0; remaining_bytes--) {
                                if (u8l >= *utf8len)
                                        return (EINVAL);

                                c = (uint32_t)u8s[u8l++];

                                if (first_b) {
                                        if (c < valid_min_2nd_byte[first_b] ||
                                            c > valid_max_2nd_byte[first_b])
                                                return (EILSEQ);
                                        first_b = 0;
                                } else if (c < UCONV_U8_BYTE_MIN ||
                                    c > UCONV_U8_BYTE_MAX) {
                                        return (EILSEQ);
                                }
                                hi = (hi << UCONV_U8_BIT_SHIFT) |
                                    (c & UCONV_U8_BIT_MASK);
                        }
                }

                if (u32l >= *utf32len)
                        return (E2BIG);

                u32s[u32l++] = (outendian) ? hi : BSWAP_32(hi);
        }

        *utf32len = u32l;
        *utf8len = u8l;

        return (0);
}