kc3-lang/gnulib/lib/unistr/u8-mblen.c

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• Hash : 32a72f45
  Author :
  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

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• lib/unistr/u8-mblen.c

• /* Look at first character in UTF-8 string.
     Copyright (C) 1999-2000, 2002, 2006-2007, 2009-2023 Free Software
     Foundation, Inc.
     Written by Bruno Haible <bruno@clisp.org>, 2002.
  
     This file is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as
     published by the Free Software Foundation; either version 2.1 of the
     License, or (at your option) any later version.
  
     This file is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  
  #include <config.h>
  
  /* Specification.  */
  #include "unistr.h"
  
  int
  u8_mblen (const uint8_t *s, size_t n)
  {
    if (n > 0)
      {
        /* Keep in sync with unistr.h and u8-mbtouc-aux.c.  */
        uint8_t c = *s;
  
        if (c < 0x80)
          return (c != 0 ? 1 : 0);
        if (c >= 0xc2)
          {
            if (c < 0xe0)
              {
                if (n >= 2
                    && (s[1] ^ 0x80) < 0x40)
                  return 2;
              }
            else if (c < 0xf0)
              {
                if (n >= 3
                    && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
                    && (c >= 0xe1 || s[1] >= 0xa0)
                    && (c != 0xed || s[1] < 0xa0))
                  return 3;
              }
            else if (c < 0xf8)
              {
                if (n >= 4
                    && (s[1] ^ 0x80) < 0x40 && (s[2] ^ 0x80) < 0x40
                    && (s[3] ^ 0x80) < 0x40
                    && (c >= 0xf1 || s[1] >= 0x90)
                    && (c < 0xf4 || (c == 0xf4 && s[1] < 0x90)))
                  return 4;
              }
          }
      }
    /* invalid or incomplete multibyte character */
    return -1;
  }
  

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