newlib/libc/stdlib/mbtowc.c

   1 /*
   2 FUNCTION
   3 <<mbtowc>>---minimal multibyte to wide char converter
   4
   5 INDEX
   6         mbtowc
   7
   8 SYNOPSIS
   9         #include <stdlib.h>
  10         int mbtowc(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 <<mbtowc>>.  In this case,
  15 only ``multi-byte character sequences'' recognized are single bytes,
  16 and they are ``converted'' to themselves.
  17 Each call to <<mbtowc>> copies one character from <<*<[s]>>> to
  18 <<*<[pwc]>>>, unless <[s]> is a null pointer.  The argument n
  19 is ignored.
  20
  21 When _MB_CAPABLE is defined, this routine calls <<_mbtowc_r>> to perform
  22 the conversion, passing a state variable to allow state dependent
  23 decoding.  The result is based on the locale setting which may
  24 be restricted to a defined set of locales.
  25
  26 RETURNS
  27 This implementation of <<mbtowc>> returns <<0>> if
  28 <[s]> is <<NULL>> or is the empty string;
  29 it returns <<1>> if not _MB_CAPABLE or
  30 the character is a single-byte character; it returns <<-1>>
  31 if n is <<0>> or the multi-byte character is invalid;
  32 otherwise it returns the number of bytes in the multibyte character.
  33 If the return value is -1, no changes are made to the <<pwc>>
  34 output string.  If the input is the empty string, a wchar_t nul
  35 is placed in the output string and 0 is returned.  If the input
  36 has a length of 0, no changes are made to the <<pwc>> output string.
  37
  38 PORTABILITY
  39 <<mbtowc>> is required in the ANSI C standard.  However, the precise
  40 effects vary with the locale.
  41
  42 <<mbtowc>> requires no supporting OS subroutines.
  43 */
  44
  45 #ifndef _REENT_ONLY
  46
  47 #include <newlib.h>
  48 #include <stdlib.h>
  49 #include <wchar.h>
  50 #include "local.h"
  51
  52 #ifdef _REENT_THREAD_LOCAL
  53 _Thread_local _mbstate_t _tls_mbtowc_state;
  54 #endif
  55
  56 int
  57 mbtowc (wchar_t *__restrict pwc,
  58         const char *__restrict s,
  59         size_t n)
  60 {
  61 #ifdef _MB_CAPABLE
  62   int retval = 0;
  63   struct _reent *reent = _REENT;
  64   mbstate_t *ps;
  65
  66   _REENT_CHECK_MISC(reent);
  67   ps = &(_REENT_MBTOWC_STATE(reent));
  68
  69   retval = __MBTOWC (reent, pwc, s, n, ps);
  70
  71   if (retval < 0)
  72     {
  73       ps->__count = 0;
  74       return -1;
  75     }
  76   return retval;
  77 #else /* not _MB_CAPABLE */
  78   if (s == NULL)
  79     return 0;
  80   if (n == 0)
  81     return -1;
  82   if (pwc)
  83     *pwc = (wchar_t) *s;
  84   return (*s != '\0');
  85 #endif /* not _MB_CAPABLE */
  86 }
  87
  88 #endif /* !_REENT_ONLY */
  89
  90
  91
  92