cosmopolitan/libc/str/tprecode8to16.c

61 lines
2.8 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ 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; version 2 of the License. │
│ │
│ 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, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/str/str.h"
#include "libc/str/thompike.h"
#include "libc/str/utf16.h"
/**
* Transcodes UTF-8 to UTF-16.
*
* @param dst is output buffer
* @param dstsize is shorts in dst
* @param src is NUL-terminated UTF-8 input string
* @return number of shorts written excluding NUL
*/
size_t tprecode8to16(char16_t *dst, size_t dstsize, const char *src) {
size_t i;
unsigned n;
uint64_t w;
wint_t x, y;
i = 0;
if (dstsize) {
for (;;) {
if (!(x = *src++ & 0xff)) break;
if (ThomPikeCont(x)) continue;
if (!isascii(x)) {
n = ThomPikeLen(x);
x = ThomPikeByte(x);
while (--n) {
if (!(y = *src++ & 0xff)) goto stop;
x = ThomPikeMerge(x, y);
}
}
w = EncodeUtf16(x);
while (w && i + 1 < dstsize) {
dst[i++] = w & 0xFFFF;
w >>= 16;
}
}
stop:
dst[i] = 0;
}
return i;
}