newlib/libc/stdlib/mbstowcs.c

   1 /*
   2 FUNCTION
   3 <<mbstowcs>>---minimal multibyte string to wide char converter
   4
   5 INDEX
   6         mbstowcs
   7
   8 SYNOPSIS
   9         #include <stdlib.h>
  10         int mbstowcs(wchar_t *restrict <[pwc]>, const char *restrict <[s]>, size_t <[n]>);
  11
  12 DESCRIPTION
  13 When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
  14 implementation of <<mbstowcs>>.  In this case, the
  15 only ``multi-byte character sequences'' recognized are single bytes,
  16 and they are ``converted'' to wide-char versions simply by byte
  17 extension.
  18
  19 When _MB_CAPABLE is defined, this routine calls <<_mbstowcs_r>> to perform
  20 the conversion, passing a state variable to allow state dependent
  21 decoding.  The result is based on the locale setting which may
  22 be restricted to a defined set of locales.
  23
  24 RETURNS
  25 This implementation of <<mbstowcs>> returns <<0>> if
  26 <[s]> is <<NULL>> or is the empty string;
  27 it returns <<-1>> if _MB_CAPABLE and one of the
  28 multi-byte characters is invalid or incomplete;
  29 otherwise it returns the minimum of: <<n>> or the
  30 number of multi-byte characters in <<s>> plus 1 (to
  31 compensate for the nul character).
  32 If the return value is -1, the state of the <<pwc>> string is
  33 indeterminate.  If the input has a length of 0, the output
  34 string will be modified to contain a wchar_t nul terminator.
  35
  36 PORTABILITY
  37 <<mbstowcs>> is required in the ANSI C standard.  However, the precise
  38 effects vary with the locale.
  39
  40 <<mbstowcs>> requires no supporting OS subroutines.
  41 */
  42
  43 #ifndef _REENT_ONLY
  44
  45 #include <newlib.h>
  46 #include <stdlib.h>
  47 #include <wchar.h>
  48
  49 size_t
  50 mbstowcs (wchar_t *__restrict pwcs,
  51         const char *__restrict s,
  52         size_t n)
  53 {
  54 #ifdef _MB_CAPABLE
  55   mbstate_t state;
  56   state.__count = 0;
  57
  58   return _mbstowcs_r (_REENT, pwcs, s, n, &state);
  59 #else /* not _MB_CAPABLE */
  60
  61   int count = 0;
  62
  63   if (n != 0) {
  64     do {
  65       if ((*pwcs++ = (wchar_t) *s++) == 0)
  66         break;
  67       count++;
  68     } while (--n != 0);
  69   }
  70
  71   return count;
  72 #endif /* not _MB_CAPABLE */
  73 }
  74
  75 #endif /* !_REENT_ONLY */