newlib/libc/string/strxfrm.c

   1 /*
   2 FUNCTION
   3         <<strxfrm>>---transform string
   4
   5 INDEX
   6         strxfrm
   7
   8 SYNOPSIS
   9         #include <string.h>
  10         size_t strxfrm(char *restrict <[s1]>, const char *restrict <[s2]>,
  11                        size_t <[n]>);
  12
  13 DESCRIPTION
  14         This function transforms the string pointed to by <[s2]> and
  15         places the resulting string into the array pointed to by
  16         <[s1]>. The transformation is such that if the <<strcmp>>
  17         function is applied to the two transformed strings, it returns
  18         a value greater than, equal to, or less than zero,
  19         correspoinding to the result of a <<strcoll>> function applied
  20         to the same two original strings.
  21
  22         No more than <[n]> characters are placed into the resulting
  23         array pointed to by <[s1]>, including the terminating null
  24         character. If <[n]> is zero, <[s1]> may be a null pointer. If
  25         copying takes place between objects that overlap, the behavior
  26         is undefined.
  27
  28         (NOT Cygwin:) The current implementation of <<strxfrm>> simply copies
  29         the input and does not support any language-specific transformations.
  30
  31 RETURNS
  32         The <<strxfrm>> function returns the length of the transformed string
  33         (not including the terminating null character). If the value returned
  34         is <[n]> or more, the contents of the array pointed to by
  35         <[s1]> are indeterminate.
  36
  37 PORTABILITY
  38 <<strxfrm>> is ANSI C.
  39
  40 <<strxfrm>> requires no supporting OS subroutines.
  41
  42 QUICKREF
  43         strxfrm ansi pure
  44 */
  45
  46 #include <string.h>
  47
  48 size_t
  49 strxfrm (char *__restrict s1,
  50         const char *__restrict s2,
  51         size_t n)
  52 {
  53   size_t res;
  54   res = 0;
  55   while (n-- > 0)
  56     {
  57       if ((*s1++ = *s2++) != '\0')
  58         ++res;
  59       else
  60         return res;
  61     }
  62   while (*s2)
  63     {
  64       ++s2;
  65       ++res;
  66     }
  67
  68   return res;
  69 }