newlib/libc/string/strcpy.c

   1 /*
   2 FUNCTION
   3         <<strcpy>>---copy string
   4
   5 INDEX
   6         strcpy
   7
   8 SYNOPSIS
   9         #include <string.h>
  10         char *strcpy(char *<[dst]>, const char *<[src]>);
  11
  12 DESCRIPTION
  13         <<strcpy>> 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 the initial value of <[dst]>.
  19
  20 PORTABILITY
  21 <<strcpy>> is ANSI C.
  22
  23 <<strcpy>> requires no supporting OS subroutines.
  24
  25 QUICKREF
  26         strcpy ansi pure
  27 */
  28
  29 #include <string.h>
  30 #include <limits.h>
  31
  32 /*SUPPRESS 560*/
  33 /*SUPPRESS 530*/
  34
  35 /* Nonzero if either X or Y is not aligned on a "long" boundary.  */
  36 #define UNALIGNED(X, Y) \
  37   (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
  38
  39 #if LONG_MAX == 2147483647L
  40 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
  41 #else
  42 #if LONG_MAX == 9223372036854775807L
  43 /* Nonzero if X (a long int) contains a NULL byte. */
  44 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
  45 #else
  46 #error long int is not a 32bit or 64bit type.
  47 #endif
  48 #endif
  49
  50 #ifndef DETECTNULL
  51 #error long int is not a 32bit or 64bit byte
  52 #endif
  53
  54 char*
  55 strcpy (char *dst0,
  56         const char *src0)
  57 {
  58 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
  59   char *s = dst0;
  60
  61   while (*dst0++ = *src0++)
  62     ;
  63
  64   return s;
  65 #else
  66   char *dst = dst0;
  67   const char *src = src0;
  68   long *aligned_dst;
  69   const long *aligned_src;
  70
  71   /* If SRC or DEST is unaligned, then copy bytes.  */
  72   if (!UNALIGNED (src, dst))
  73     {
  74       aligned_dst = (long*)dst;
  75       aligned_src = (long*)src;
  76
  77       /* SRC and DEST are both "long int" aligned, try to do "long int"
  78          sized copies.  */
  79       while (!DETECTNULL(*aligned_src))
  80         {
  81           *aligned_dst++ = *aligned_src++;
  82         }
  83
  84       dst = (char*)aligned_dst;
  85       src = (char*)aligned_src;
  86     }
  87
  88   while ((*dst++ = *src++))
  89     ;
  90   return dst0;
  91 #endif /* not PREFER_SIZE_OVER_SPEED */
  92 }