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/*
Copyright (c) 1990 Regents of the University of California.
All rights reserved.
*/
/*
FUNCTION
<<mbstowcs>>---minimal multibyte string to wide char converter
INDEX
mbstowcs
SYNOPSIS
#include <stdlib.h>
int mbstowcs(wchar_t *restrict <[pwc]>, const char *restrict <[s]>, size_t <[n]>);
DESCRIPTION
When __MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of <<mbstowcs>>. In this case, the
only ``multi-byte character sequences'' recognized are single bytes,
and they are ``converted'' to wide-char versions simply by byte
extension.
When __MB_CAPABLE is defined, this uses a state variable to allow state
dependent decoding. The result is based on the locale setting which
may be restricted to a defined set of locales.
RETURNS
This implementation of <<mbstowcs>> returns <<0>> if
<[s]> is <<NULL>> or is the empty string;
it returns <<-1>> if __MB_CAPABLE and one of the
multi-byte characters is invalid or incomplete;
otherwise it returns the minimum of: <<n>> or the
number of multi-byte characters in <<s>> plus 1 (to
compensate for the nul character).
If the return value is -1, the state of the <<pwc>> string is
indeterminate. If the input has a length of 0, the output
string will be modified to contain a wchar_t nul terminator.
PORTABILITY
<<mbstowcs>> is required in the ANSI C standard. However, the precise
effects vary with the locale.
<<mbstowcs>> requires no supporting OS subroutines.
*/
#include <stdlib.h>
#include <wchar.h>
#include "local.h"
size_t
mbstowcs(wchar_t * __restrict pwcs, const char * __restrict s, size_t n)
{
#ifdef __MB_CAPABLE
mbstate_t state;
state.__count = 0;
size_t ret = 0;
char *t = (char *)s;
int bytes;
if (!pwcs)
n = (size_t)1; /* Value doesn't matter as long as it's not 0. */
while (n > 0) {
bytes = __MBTOWC(pwcs, t, MB_CUR_MAX, &state);
if (bytes < 0) {
state.__count = 0;
errno = EILSEQ;
return -1;
} else if (bytes == 0)
break;
t += bytes;
++ret;
if (pwcs) {
++pwcs;
--n;
}
}
return ret;
#else /* not __MB_CAPABLE */
int count = 0;
if (n != 0) {
do {
if ((*pwcs++ = (wchar_t)*s++) == 0)
break;
count++;
} while (--n != 0);
}
return count;
#endif /* not __MB_CAPABLE */
}
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