Back to index

glibc  2.9
mempcpy.c
Go to the documentation of this file.
00001 /* Copy memory to memory until the specified number of bytes
00002    has been copied, return pointer to following byte.
00003    Overlap is NOT handled correctly.
00004    Copyright (C) 1991, 1997, 1998, 2002, 2004 Free Software Foundation, Inc.
00005    This file is part of the GNU C Library.
00006    Contributed by Torbjorn Granlund (tege@sics.se).
00007 
00008    The GNU C Library is free software; you can redistribute it and/or
00009    modify it under the terms of the GNU Lesser General Public
00010    License as published by the Free Software Foundation; either
00011    version 2.1 of the License, or (at your option) any later version.
00012 
00013    The GNU C Library is distributed in the hope that it will be useful,
00014    but WITHOUT ANY WARRANTY; without even the implied warranty of
00015    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016    Lesser General Public License for more details.
00017 
00018    You should have received a copy of the GNU Lesser General Public
00019    License along with the GNU C Library; if not, write to the Free
00020    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00021    02111-1307 USA.  */
00022 
00023 #include <string.h>
00024 #include <memcopy.h>
00025 #include <pagecopy.h>
00026 
00027 #undef mempcpy
00028 #undef __mempcpy
00029 
00030 void *
00031 __mempcpy (dstpp, srcpp, len)
00032      void *dstpp;
00033      const void *srcpp;
00034      size_t len;
00035 {
00036   unsigned long int dstp = (long int) dstpp;
00037   unsigned long int srcp = (long int) srcpp;
00038 
00039   /* Copy from the beginning to the end.  */
00040 
00041   /* If there not too few bytes to copy, use word copy.  */
00042   if (len >= OP_T_THRES)
00043     {
00044       /* Copy just a few bytes to make DSTP aligned.  */
00045       len -= (-dstp) % OPSIZ;
00046       BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ);
00047 
00048       /* Copy whole pages from SRCP to DSTP by virtual address manipulation,
00049         as much as possible.  */
00050 
00051       PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len);
00052 
00053       /* Copy from SRCP to DSTP taking advantage of the known alignment of
00054         DSTP.  Number of bytes remaining is put in the third argument,
00055         i.e. in LEN.  This number may vary from machine to machine.  */
00056 
00057       WORD_COPY_FWD (dstp, srcp, len, len);
00058 
00059       /* Fall out and copy the tail.  */
00060     }
00061 
00062   /* There are just a few bytes to copy.  Use byte memory operations.  */
00063   BYTE_COPY_FWD (dstp, srcp, len);
00064 
00065   return (void *) dstp;
00066 }
00067 libc_hidden_def (__mempcpy)
00068 weak_alias (__mempcpy, mempcpy)
00069 libc_hidden_builtin_def (mempcpy)