/* Iterate over previous character in UTF-16 string. Copyright (C) 2002, 2006-2007 Free Software Foundation, Inc. Written by Bruno Haible , 2002. This program is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ #include /* Specification. */ #include "unistr.h" const uint16_t * u16_prev (ucs4_t *puc, const uint16_t *s, const uint16_t *start) { /* Keep in sync with unistr.h and utf16-ucs4.c. */ if (s != start) { uint16_t c_1 = s[-1]; if (c_1 < 0xd800 || c_1 >= 0xe000) { *puc = c_1; return s - 1; } #if CONFIG_UNICODE_SAFETY if (c_1 >= 0xdc00) #endif if (s - 1 != start) { uint16_t c_2 = s[-2]; #if CONFIG_UNICODE_SAFETY if (c_2 >= 0xd800 && c_2 < 0xdc00) #endif { *puc = 0x10000 + ((c_2 - 0xd800) << 10) + (c_1 - 0xdc00); return s - 2; } } } return NULL; }