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