1/* Compare UTF-16 strings. 2 Copyright (C) 1999, 2002, 2006, 2009-2010 Free Software Foundation, Inc. 3 Written by Bruno Haible <bruno@clisp.org>, 2002. 4 5 This program is free software: you can redistribute it and/or modify it 6 under the terms of the GNU Lesser General Public License as published 7 by the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18#include <config.h> 19 20/* Specification. */ 21#include "unistr.h" 22 23int 24u16_strcmp (const uint16_t *s1, const uint16_t *s2) 25{ 26 /* Note that the UTF-16 encoding does NOT preserve lexicographic order. 27 Namely, if uc1 is a 16-bit character and [uc2a,uc2b] is a surrogate pair, 28 we must enforce uc1 < [uc2a,uc2b], even if uc1 > uc2a. */ 29 for (;;) 30 { 31 uint16_t c1 = *s1++; 32 uint16_t c2 = *s2++; 33 if (c1 != 0 && c1 == c2) 34 continue; 35 if (c1 < 0xd800 || c1 >= 0xe000) 36 { 37 if (!(c2 < 0xd800 || c2 >= 0xe000)) 38 /* c2 is a surrogate, but c1 is not. */ 39 return -1; 40 } 41 else 42 { 43 if (c2 < 0xd800 || c2 >= 0xe000) 44 /* c1 is a surrogate, but c2 is not. */ 45 return 1; 46 } 47 return (int)c1 - (int)c2; 48 /* > 0 if c1 > c2, < 0 if c1 < c2. */ 49 } 50} 51