rm_/lib/unistr/u8-uctomb-aux.c

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/* Conversion UCS-4 to UTF-8.
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Copyright (C) 2002, 2006-2007, 2009-2022 Free Software Foundation, Inc.
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Written by Bruno Haible <bruno@clisp.org>, 2002.
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This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
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This file 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 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 <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "unistr.h"
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#include "attribute.h"
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int
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u8_uctomb_aux (uint8_t *s, ucs4_t uc, ptrdiff_t n)
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{
int count;
if (uc < 0x80)
/* The case n >= 1 is already handled by the caller. */
return -2;
else if (uc < 0x800)
count = 2;
else if (uc < 0x10000)
{
if (uc < 0xd800 || uc >= 0xe000)
count = 3;
else
return -1;
}
else if (uc < 0x110000)
count = 4;
else
return -1;
if (n < count)
return -2;
switch (count) /* note: code falls through cases! */
{
case 4: s[3] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x10000;
FALLTHROUGH;
case 3: s[2] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0x800;
FALLTHROUGH;
case 2: s[1] = 0x80 | (uc & 0x3f); uc = uc >> 6; uc |= 0xc0;
/*case 1:*/ s[0] = uc;
}
return count;
}