lib/uniwidth/u16-width.c

   1 /* Determine display width of UTF-16 string.
   2    Copyright (C) 2001-2002, 2006-2007, 2009-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2002.
   4
   5    This file is free software.
   6    It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+".
   7    You can redistribute it and/or modify it under either
   8      - the terms of the GNU Lesser General Public License as published
   9        by the Free Software Foundation, either version 3, or (at your
  10        option) any later version, or
  11      - the terms of the GNU General Public License as published by the
  12        Free Software Foundation; either version 2, or (at your option)
  13        any later version, or
  14      - the same dual license "the GNU LGPLv3+ or the GNU GPLv2+".
  15
  16    This file is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19    Lesser General Public License and the GNU General Public License
  20    for more details.
  21
  22    You should have received a copy of the GNU Lesser General Public
  23    License and of the GNU General Public License along with this
  24    program.  If not, see <https://www.gnu.org/licenses/>.  */
  25
  26 #include <config.h>
  27
  28 /* Specification.  */
  29 #include "uniwidth.h"
  30
  31 #include "unistr.h"
  32
  33 int
  34 u16_width (const uint16_t *s, size_t n, const char *encoding)
  35 {
  36   const uint16_t *s_end = s + n;
  37   int width = 0;
  38
  39   while (s < s_end)
  40     {
  41       ucs4_t uc;
  42       int w;
  43
  44       s += u16_mbtouc_unsafe (&uc, s, s_end - s);
  45
  46       if (uc == 0)
  47         break; /* end of string reached */
  48
  49       w = uc_width (uc, encoding);
  50       if (w >= 0) /* ignore control characters in the string */
  51         width += w;
  52     }
  53
  54   return width;
  55 }