newlib/libc/stdlib/wcstombs.c

   1 /*
   2 FUNCTION
   3 <<wcstombs>>---minimal wide char string to multibyte string converter
   4
   5 INDEX
   6         wcstombs
   7
   8 SYNOPSIS
   9         #include <stdlib.h>
  10         size_t wcstombs(char *restrict <[s]>, const wchar_t *restrict <[pwc]>, size_t <[n]>);
  11
  12 DESCRIPTION
  13 When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
  14 implementation of <<wcstombs>>.  In this case,
  15 all wide-characters are expected to represent single bytes and so
  16 are converted simply by casting to char.
  17
  18 When _MB_CAPABLE is defined, this routine calls <<_wcstombs_r>> to perform
  19 the conversion, passing a state variable to allow state dependent
  20 decoding.  The result is based on the locale setting which may
  21 be restricted to a defined set of locales.
  22
  23 RETURNS
  24 This implementation of <<wcstombs>> returns <<0>> if
  25 <[s]> is <<NULL>> or is the empty string;
  26 it returns <<-1>> if _MB_CAPABLE and one of the
  27 wide-char characters does not represent a valid multi-byte character;
  28 otherwise it returns the minimum of: <<n>> or the
  29 number of bytes that are transferred to <<s>>, not including the
  30 nul terminator.
  31
  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 if
  35 <<n>> > 0.
  36
  37 PORTABILITY
  38 <<wcstombs>> is required in the ANSI C standard.  However, the precise
  39 effects vary with the locale.
  40
  41 <<wcstombs>> requires no supporting OS subroutines.
  42 */
  43
  44 #ifndef _REENT_ONLY
  45
  46 #include <newlib.h>
  47 #include <stdlib.h>
  48 #include <wchar.h>
  49
  50 size_t
  51 wcstombs (char          *__restrict s,
  52         const wchar_t *__restrict pwcs,
  53         size_t         n)
  54 {
  55 #ifdef _MB_CAPABLE
  56   mbstate_t state;
  57   state.__count = 0;
  58
  59   return _wcstombs_r (_REENT, s, pwcs, n, &state);
  60 #else /* not _MB_CAPABLE */
  61   int count = 0;
  62
  63   if (n != 0) {
  64     do {
  65       if ((*s++ = (char) *pwcs++) == 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 */