newlib/libc/string/stpcpy.c

   1 /*
   2 FUNCTION
   3         <<stpcpy>>---copy string returning a pointer to its end
   4
   5 INDEX
   6         stpcpy
   7
   8 SYNOPSIS
   9         #include <string.h>
  10         char *stpcpy(char *restrict <[dst]>, const char *restrict <[src]>);
  11
  12 DESCRIPTION
  13         <<stpcpy>> copies the string pointed to by <[src]>
  14         (including the terminating null character) to the array
  15         pointed to by <[dst]>.
  16
  17 RETURNS
  18         This function returns a pointer to the end of the destination string,
  19         thus pointing to the trailing '\0'.
  20
  21 PORTABILITY
  22 <<stpcpy>> is a GNU extension, candidate for inclusion into POSIX/SUSv4.
  23
  24 <<stpcpy>> requires no supporting OS subroutines.
  25
  26 QUICKREF
  27         stpcpy gnu
  28 */
  29
  30 #include <string.h>
  31 #include <limits.h>
  32
  33 /*SUPPRESS 560*/
  34 /*SUPPRESS 530*/
  35
  36 /* Nonzero if either X or Y is not aligned on a "long" boundary.  */
  37 #define UNALIGNED(X, Y) \
  38   (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
  39
  40 #if LONG_MAX == 2147483647L
  41 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
  42 #else
  43 #if LONG_MAX == 9223372036854775807L
  44 /* Nonzero if X (a long int) contains a NULL byte. */
  45 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
  46 #else
  47 #error long int is not a 32bit or 64bit type.
  48 #endif
  49 #endif
  50
  51 #ifndef DETECTNULL
  52 #error long int is not a 32bit or 64bit byte
  53 #endif
  54
  55 char*
  56 stpcpy (char *__restrict dst,
  57         const char *__restrict src)
  58 {
  59 #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
  60   long *aligned_dst;
  61   const long *aligned_src;
  62
  63   /* If SRC or DEST is unaligned, then copy bytes.  */
  64   if (!UNALIGNED (src, dst))
  65     {
  66       aligned_dst = (long*)dst;
  67       aligned_src = (long*)src;
  68
  69       /* SRC and DEST are both "long int" aligned, try to do "long int"
  70          sized copies.  */
  71       while (!DETECTNULL(*aligned_src))
  72         {
  73           *aligned_dst++ = *aligned_src++;
  74         }
  75
  76       dst = (char*)aligned_dst;
  77       src = (char*)aligned_src;
  78     }
  79 #endif /* not PREFER_SIZE_OVER_SPEED */
  80
  81   while ((*dst++ = *src++))
  82     ;
  83   return --dst;
  84 }