string/strcat.c

   1 /* Copyright (C) 1991-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <string.h>
  19
  20 #undef strcat
  21
  22 /* Append SRC on the end of DEST.  */
  23 char *
  24 strcat (char *dest, const char *src)
  25 {
  26   char *s1 = dest;
  27   const char *s2 = src;
  28   char c;
  29
  30   /* Find the end of the string.  */
  31   do
  32     c = *s1++;
  33   while (c != '\0');
  34
  35   /* Make S1 point before the next character, so we can increment
  36      it while memory is read (wins on pipelined cpus).  */
  37   s1 -= 2;
  38
  39   do
  40     {
  41       c = *s2++;
  42       *++s1 = c;
  43     }
  44   while (c != '\0');
  45
  46   return dest;
  47 }
  48 libc_hidden_builtin_def (strcat)