newlib-2.4.0: wide character strings

git-svn-id: svn://kolibrios.org@6557 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/newlib/libc/string/wcswidth.c

@@ -0,0 +1,73 @@
+/*
+FUNCTION
+	<<wcswidth>>---number of column positions of a wide-character string
+	
+INDEX
+	wcswidth
+
+ANSI_SYNOPSIS
+	#include <wchar.h>
+	int wcswidth(const wchar_t *<[pwcs]>, size_t <[n]>);
+
+TRAD_SYNOPSIS
+	#include <wchar.h>
+	int wcswidth(<[pwcs]>, <[n]>)
+	wchar_t *<[wc]>;
+	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
+_DEFUN (wcswidth, (pwcs, n),
+	_CONST wchar_t *pwcs _AND
+	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;
+}