46 lines
2.7 KiB
C
46 lines
2.7 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ 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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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/errno.h"
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#include "libc/str/str.h"
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/**
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* Decodes UTF-16 character.
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*
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* @param s is a NUL-terminated string
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* @return number of bytes (NUL counts as 1) or -1 w/ errno
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* @note synchronization is performed to skip leading continuations;
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* canonicalization and validation are performed to some extent
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*/
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unsigned(getutf16)(const char16_t *p, wint_t *wc) {
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unsigned skip = 0;
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while ((p[skip] & UTF16_MASK) == UTF16_CONT) skip++;
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if ((p[skip] & UTF16_MASK) != UTF16_MOAR) {
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*wc = p[skip];
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return skip + 1;
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} else if ((p[skip + 1] & UTF16_MASK) != UTF16_CONT) {
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*wc = INVALID_CODEPOINT;
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return -1;
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} else {
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*wc = 0x10000 + ((((unsigned)p[skip + 0] - 0xd800) << 10) +
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((unsigned)p[skip + 1] - 0xdc00));
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return skip + 2;
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}
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}
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