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/*
* Copyright (c) 2016, Linaro Limited
* 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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 "utf8.h"
uint32_t utf8_get_code_point(const char *utf8_str, size_t *idx)
{
const uint8_t *p = (const uint8_t *)utf8_str + *idx;
uint8_t first = p[0];
uint8_t first_mask;
uint8_t first_prefix;
size_t n;
size_t m;
uint32_t cp;
if (!first)
return 0;
if (!(p[0] & 0x80)) {
/* 0vvv_vvvv */
(*idx)++;
return p[0];
}
/*
* n = 1:
* first_mask = 0xe0, first_prefix = 0xc0
* 110v_vvvv 10vv_vvvv
*
* n = 2:
* first_mask = 0xf0, first_prefix = 0xe0
* 1110_vvvv 10vv_vvvv 10vv_vvvv
*
* n = 3:
* first_mask = 0xf8, first_prefix = 0xf0
* 1111_0vvv 10vv_vvvv 10vv_vvvv 10vv_vvvv
*
* n = 4:
* first_mask = 0xfc, first_prefix = 0xf8
* 1111_10vv 10vv_vvvv 10vv_vvvv 10vv_vvvv 10vv_vvvv
*
* n = 5:
* first_mask = 0xfe, first_prefix = 0xfc
* 1111_110v 10vv_vvvv 10vv_vvvv 10vv_vvvv 10vv_vvvv 10vv_vvvv
*/
first_mask = 0xe0;
first_prefix = 0xc0;
for (n = 1; n < 6 && (p[n] & 0xc0) == 0x80; n++) {
if ((first & first_mask) == first_prefix) {
cp = first & ~first_mask;
for (m = 1; m <= n; m++) {
cp <<= 6;
cp |= p[m] & 0x3f;
}
(*idx) += n + 1;
return cp;
}
first_prefix = first_mask;
first_mask = (first_mask >> 1) | 0x80;
}
return UTF8_INVALID_CODE;
}
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