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/*
FUNCTION
<<wcswidth>>---number of column positions of a wide-character string
INDEX
wcswidth
SYNOPSIS
#include <wchar.h>
int wcswidth(const wchar_t *<[pwcs]>, size_t <[n]>);
DESCRIPTION
The <<wcswidth>> function shall determine the number of column
positions required for <[n]> wide-character codes (or fewer than <[n]>
wide-character codes if a null wide-character code is encountered
before <[n]> wide-character codes are exhausted) in the string pointed
to by <[pwcs]>.
RETURNS
The <<wcswidth>> function either shall return 0 (if <[pwcs]> points to a
null wide-character code), or return the number of column positions
to be occupied by the wide-character string pointed to by <[pwcs]>, or
return -1 (if any of the first <[n]> wide-character codes in the
wide-character string pointed to by <[pwcs]> is not a printable
wide-character code).
PORTABILITY
<<wcswidth>> has been introduced in the Single UNIX Specification Volume 2.
<<wcswidth>> has been marked as an extension in the Single UNIX Specification Volume 3.
*/
#include <_ansi.h>
#include <wchar.h>
#include "local.h"
int
wcswidth (const wchar_t *pwcs,
size_t n)
{
int w, len = 0;
if (!pwcs || n == 0)
return 0;
do {
wint_t wi = *pwcs;
#ifdef _MB_CAPABLE
wi = _jp2uc (wi);
/* First half of a surrogate pair? */
if (sizeof (wchar_t) == 2 && wi >= 0xd800 && wi <= 0xdbff)
{
wint_t wi2;
/* Extract second half and check for validity. */
if (--n == 0 || (wi2 = _jp2uc (*++pwcs)) < 0xdc00 || wi2 > 0xdfff)
return -1;
/* Compute actual unicode value to use in call to __wcwidth. */
wi = (((wi & 0x3ff) << 10) | (wi2 & 0x3ff)) + 0x10000;
}
#endif /* _MB_CAPABLE */
if ((w = __wcwidth (wi)) < 0)
return -1;
len += w;
} while (*pwcs++ && --n > 0);
return len;
}
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