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1cd4fffcde
* .x-sc_prohibit_S_IS_definition: New file. * m4/gnulib-cache.m4: Add `sys_stat'. * libguile/filesys.c: Remove `S_IS*' macro definitions for Ultrix and MinGW.
93 lines
3 KiB
C
93 lines
3 KiB
C
/* Iterate over previous character in UTF-8 string.
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Copyright (C) 2002, 2006-2007 Free Software Foundation, Inc.
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Written by Bruno Haible <bruno@clisp.org>, 2002.
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This program is free software: you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published
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by the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#include "unistr.h"
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const uint8_t *
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u8_prev (ucs4_t *puc, const uint8_t *s, const uint8_t *start)
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{
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/* Keep in sync with unistr.h and utf8-ucs4.c. */
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if (s != start)
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{
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uint8_t c_1 = s[-1];
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if (c_1 < 0x80)
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{
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*puc = c_1;
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return s - 1;
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}
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#if CONFIG_UNICODE_SAFETY
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if ((c_1 ^ 0x80) < 0x40)
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#endif
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if (s - 1 != start)
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{
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uint8_t c_2 = s[-2];
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if (c_2 >= 0xc2 && c_2 < 0xe0)
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{
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*puc = ((unsigned int) (c_2 & 0x1f) << 6)
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| (unsigned int) (c_1 ^ 0x80);
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return s - 2;
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}
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#if CONFIG_UNICODE_SAFETY
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if ((c_2 ^ 0x80) < 0x40)
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#endif
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if (s - 2 != start)
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{
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uint8_t c_3 = s[-3];
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if (c_3 >= 0xe0 && c_3 < 0xf0
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#if CONFIG_UNICODE_SAFETY
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&& (c_3 >= 0xe1 || c_2 >= 0xa0)
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&& (c_3 != 0xed || c_2 < 0xa0)
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#endif
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)
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{
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*puc = ((unsigned int) (c_3 & 0x0f) << 12)
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| ((unsigned int) (c_2 ^ 0x80) << 6)
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| (unsigned int) (c_1 ^ 0x80);
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return s - 3;
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}
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#if CONFIG_UNICODE_SAFETY
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if ((c_3 ^ 0x80) < 0x40)
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#endif
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if (s - 3 != start)
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{
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uint8_t c_4 = s[-4];
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if (c_4 >= 0xf0 && c_4 < 0xf8
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#if CONFIG_UNICODE_SAFETY
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&& (c_4 >= 0xf1 || c_3 >= 0x90)
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&& (c_4 < 0xf4 || (c_4 == 0xf4 && c_3 < 0x90))
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#endif
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)
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{
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*puc = ((unsigned int) (c_4 & 0x07) << 18)
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| ((unsigned int) (c_3 ^ 0x80) << 12)
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| ((unsigned int) (c_2 ^ 0x80) << 6)
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| (unsigned int) (c_1 ^ 0x80);
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return s - 4;
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}
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}
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}
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}
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}
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return NULL;
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}
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