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 /*

  * Copyright © 2011,2012  Google, Inc.

  *

  *  This is part of HarfBuzz, a text shaping library.

  *

  * Permission is hereby granted, without written agreement and without

  * license or royalty fees, to use, copy, modify, and distribute this

  * software and its documentation for any purpose, provided that the

  * above copyright notice and the following two paragraphs appear in

  * all copies of this software.

  *

  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR

  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN

  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

  * DAMAGE.

  *

  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO

  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

  *

  * Google Author(s): Behdad Esfahbod

  */

 #ifndef HB_UTF_PRIVATE_HH

 #define HB_UTF_PRIVATE_HH

 #include "hb-private.hh"

 /* UTF-8 */

 #define HB_UTF8_COMPUTE(Char, Mask, Len) \

   if (Char < 128) { Len = 1; Mask = 0x7f; } \

   else if ((Char & 0xe0) == 0xc0) { Len = 2; Mask = 0x1f; } \

   else if ((Char & 0xf0) == 0xe0) { Len = 3; Mask = 0x0f; } \

   else if ((Char & 0xf8) == 0xf0) { Len = 4; Mask = 0x07; } \

   else Len = 0;

 static inline const uint8_t *

 hb_utf_next (const uint8_t *text,

 	     const uint8_t *end,

 	     hb_codepoint_t *unicode)

 {

   hb_codepoint_t c = *text, mask;

   unsigned int len;

   /* TODO check for overlong sequences? */

   HB_UTF8_COMPUTE (c, mask, len);

   if (unlikely (!len || (unsigned int) (end - text) < len)) {

     *unicode = -1;

     return text + 1;

   } else {

     hb_codepoint_t result;

     unsigned int i;

     result = c & mask;

     for (i = 1; i < len; i++)

       {

 	if (unlikely ((text[i] & 0xc0) != 0x80))

 	  {

 	    *unicode = -1;

 	    return text + 1;

 	  }

 	result <<= 6;

 	result |= (text[i] & 0x3f);

       }

     *unicode = result;

     return text + len;

   }

 }

 static inline const uint8_t *

 hb_utf_prev (const uint8_t *text,

 	     const uint8_t *start,

 	     hb_codepoint_t *unicode)

 {

   const uint8_t *end = text--;

   while (start < text && (*text & 0xc0) == 0x80 && end - text < 4)

     text--;

   hb_codepoint_t c = *text, mask;

   unsigned int len;

   /* TODO check for overlong sequences? */

   HB_UTF8_COMPUTE (c, mask, len);

   if (unlikely (!len || (unsigned int) (end - text) != len)) {

     *unicode = -1;

     return end - 1;

   } else {

     hb_codepoint_t result;

     unsigned int i;

     result = c & mask;

     for (i = 1; i < len; i++)

       {

 	result <<= 6;

 	result |= (text[i] & 0x3f);

       }

     *unicode = result;

     return text;

   }

 }

 static inline unsigned int

 hb_utf_strlen (const uint8_t *text)

 {

   return strlen ((const char *) text);

 }

 /* UTF-16 */

 static inline const uint16_t *

 hb_utf_next (const uint16_t *text,

 	     const uint16_t *end,

 	     hb_codepoint_t *unicode)

 {

   hb_codepoint_t c = *text++;

   if (unlikely (hb_in_range<hb_codepoint_t> (c, 0xd800, 0xdbff)))

   {

     /* high surrogate */

     hb_codepoint_t l;

     if (text < end && ((l = *text), likely (hb_in_range<hb_codepoint_t> (l, 0xdc00, 0xdfff))))

     {

       /* low surrogate */

       *unicode = (c << 10) + l - ((0xd800 << 10) - 0x10000 + 0xdc00);

        text++;

     } else

       *unicode = -1;

   } else

     *unicode = c;

   return text;

 }

 static inline const uint16_t *

 hb_utf_prev (const uint16_t *text,

 	     const uint16_t *start,

 	     hb_codepoint_t *unicode)

 {

   hb_codepoint_t c = *--text;

   if (unlikely (hb_in_range<hb_codepoint_t> (c, 0xdc00, 0xdfff)))

   {

     /* low surrogate */

     hb_codepoint_t h;

     if (start < text && ((h = *(text - 1)), likely (hb_in_range<hb_codepoint_t> (h, 0xd800, 0xdbff))))

     {

       /* high surrogate */

       *unicode = (h << 10) + c - ((0xd800 << 10) - 0x10000 + 0xdc00);

        text--;

     } else

       *unicode = -1;

   } else

     *unicode = c;

   return text;

 }

 static inline unsigned int

 hb_utf_strlen (const uint16_t *text)

 {

   unsigned int l = 0;

   while (*text++) l++;

   return l;

 }

 /* UTF-32 */

 static inline const uint32_t *

 hb_utf_next (const uint32_t *text,

 	     const uint32_t *end HB_UNUSED,

 	     hb_codepoint_t *unicode)

 {

   *unicode = *text++;

   return text;

 }

 static inline const uint32_t *

 hb_utf_prev (const uint32_t *text,

 	     const uint32_t *start HB_UNUSED,

 	     hb_codepoint_t *unicode)

 {

   *unicode = *--text;

   return text;

 }

 static inline unsigned int

 hb_utf_strlen (const uint32_t *text)

 {

   unsigned int l = 0;

   while (*text++) l++;

   return l;

 }

 #endif /* HB_UTF_PRIVATE_HH */