rm_/lib/unistr/u8-uctomb-aux.c
2020-09-02 16:47:03 +08:00

67 lines
1.7 KiB
C

/* Conversion UCS-4 to UTF-8.
Copyright (C) 2002, 2006-2007, 2009-2020 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2002.
This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3 of the License, 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "unistr.h"
#ifndef FALLTHROUGH
# if __GNUC__ < 7
# define FALLTHROUGH ((void) 0)
# else
# define FALLTHROUGH __attribute__ ((__fallthrough__))
# endif
#endif
int
u8_uctomb_aux (uint8_t *s, ucs4_t uc, int n)
{
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;
}