text: /*-
   * Copyright (c) 2013 Ed Schouten <ed@FreeBSD.org>
   * 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 AUTHOR 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 AUTHOR 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.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD: releng/11.0/lib/libc/locale/mbrtoc16.c 250883 2013-05-21 19:59:37Z ed $");
  
  #include <uchar.h>
  #include "xlocale_private.h"
  
  typedef struct {
  	char16_t	trail_surrogate;
  	mbstate_t	c32_mbstate;
  } _Char16State;
  
  size_t
  mbrtoc16_l(char16_t * __restrict pc16, const char * __restrict s, size_t n,
      mbstate_t * __restrict ps, locale_t locale)
  {
  	_Char16State *cs;
  	char32_t c32;
  	ssize_t len;
  
  	FIX_LOCALE(locale);
  	if (ps == NULL)
  		ps = &locale->mbrtoc16;
  	cs = (_Char16State *)ps;
  
  	/*
  	 * Call straight into mbrtoc32_l() if we don't need to return a
  	 * character value. According to the spec, if s is a null
  	 * pointer, the value of parameter pc16 is also ignored.
  	 */
  	if (pc16 == NULL || s == NULL) {
  		cs->trail_surrogate = 0;
  		return (mbrtoc32_l(NULL, s, n, &cs->c32_mbstate, locale));
  	}
  
  	/* Return the trail surrogate from the previous invocation. */
  	if (cs->trail_surrogate >= 0xdc00 && cs->trail_surrogate <= 0xdfff) {
  		*pc16 = cs->trail_surrogate;
  		cs->trail_surrogate = 0;
  		return ((size_t)-3);
  	}
  
  	len = mbrtoc32_l(&c32, s, n, &cs->c32_mbstate, locale);
  	if (len >= 0) {
  		if (c32 < 0x10000) {
  			/* Fits in one UTF-16 character. */
  			*pc16 = c32;
  		} else {
  			/* Split up in a surrogate pair. */
  			c32 -= 0x10000;
  			*pc16 = 0xd800 | (c32 >> 10);
  			cs->trail_surrogate = 0xdc00 | (c32 & 0x3ff);
  		}
  	}
  	return (len);
  }
  
  size_t
  mbrtoc16(char16_t * __restrict pc16, const char * __restrict s, size_t n,
      mbstate_t * __restrict ps)
  {
  
  	return (mbrtoc16_l(pc16, s, n, ps, __get_locale()));
  }
  