/* $NetBSD: unicode.h,v 1.7 2014/04/06 19:25:22 jakllsch Exp $ */

/*-
* Copyright (c) 2001, 2004 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*-
* Copyright (c) 1993
*      The Regents of the University of California.  All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Paul Borman at Krystal Technologies.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

/*
* Routines for handling Unicode encoded in UTF-8 form, code derived from
* src/lib/libc/locale/utf2.c.
*/
static u_int16_t wget_utf8(const char **, size_t *) __unused;
static int wput_utf8(char *, size_t, u_int16_t) __unused;

/*
* Read one UTF8-encoded character off the string, shift the string pointer
* and return the character.
*/
static u_int16_t
wget_utf8(const char **str, size_t *sz)
{
       size_t c;
       u_int16_t rune = 0;
       const char *s = *str;
       static const int _utf_count[16] = {
               1, 1, 1, 1, 1, 1, 1, 1,
               0, 0, 0, 0, 2, 2, 3, 0,
       };

       /* must be called with at least one byte remaining */
       KASSERT(*sz > 0);

       c = _utf_count[(s[0] & 0xf0) >> 4];
       if (c == 0 || c > *sz) {
   decoding_error:
               /*
                * The first character is in range 128-255 and doesn't
                * mark valid a valid UTF-8 sequence. There is not much
                * we can do with this, so handle by returning
                * the first character as if it would be a correctly
                * encoded ISO-8859-1 character.
                */
               c = 1;
       }

       switch (c) {
       case 1:
               rune = s[0] & 0xff;
               break;
       case 2:
               if ((s[1] & 0xc0) != 0x80)
                       goto decoding_error;
               rune = ((s[0] & 0x1F) << 6) | (s[1] & 0x3F);
               break;
       case 3:
               if ((s[1] & 0xC0) != 0x80 || (s[2] & 0xC0) != 0x80)
                       goto decoding_error;
               rune = ((s[0] & 0x0F) << 12) | ((s[1] & 0x3F) << 6)
                   | (s[2] & 0x3F);
               break;
       }

       *str += c;
       *sz -= c;
       return rune;
}

/*
* Encode wide character and write it to the string. 'n' specifies
* how much buffer space remains in 's'. Returns number of bytes written
* to the target string 's'.
*/
static int
wput_utf8(char *s, size_t n, u_int16_t wc)
{
       if (wc & 0xf800) {
               if (n < 3) {
                       /* bound check failure */
                       return 0;
               }

               s[0] = 0xE0 | (wc >> 12);
               s[1] = 0x80 | ((wc >> 6) & 0x3F);
               s[2] = 0x80 | ((wc) & 0x3F);
               return 3;
       } else if (wc & 0x0780) {
               if (n < 2) {
                       /* bound check failure */
                       return 0;
               }

               s[0] = 0xC0 | (wc >> 6);
               s[1] = 0x80 | ((wc) & 0x3F);
               return 2;
       } else {
               if (n < 1) {
                       /* bound check failure */
                       return 0;
               }

               s[0] = wc;
               return 1;
       }
}