sysdeps/s390/s390-32/bcopy.S

   1 /* bcopy -- copy a block from source to destination.  For IBM S390
   2    This file is part of the GNU C Library.
   3    Copyright (C) 2000, 2001 Free Software Foundation, Inc.
   4    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
   5
   6    The GNU C Library is free software  ; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation   ; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY            ; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 /*
  22  * R2 = address of source
  23  * R3 = address of destination
  24  * R4 = number of bytes to copy
  25  */
  26
  27 #include "sysdep.h"
  28 #include "asm-syntax.h"
  29
  30         .text
  31 ENTRY(__bcopy)
  32         clr     %r2,%r3             # check against destructive overlap
  33         jnl     .L0
  34         lr      %r1,%r2
  35         alr     %r1,%r4
  36         clr     %r1,%r3
  37         jh      .L2
  38 .L0:
  39         lr      %r5,%r4             # source length
  40         lr      %r4,%r2             # source address
  41         sr      %r1,%r1             # set pad byte to zero
  42         lr      %r2,%r3             # set destination
  43         lr      %r3,%r5             # destination length = source length
  44 .L1:    mvcle   %r2,%r4,0(%r1)      # thats it, MVCLE is your friend
  45         jo      .L1
  46         br      %r14
  47 .L2:                                # destructive overlay, can not use mvcle
  48         lr     %r1,%r2              # bcopy is called with source,dest
  49         lr     %r2,%r3              # memmove with dest,source! Oh, well...
  50         lr     %r3,%r1
  51         basr   %r1,0
  52 .L3:
  53 #ifdef PIC
  54         al     %r1,.L4-.L3(%r1)     # get address of global offset table
  55                                     # load address of memmove
  56         l      %r1,memmove@GOT12(%r1)
  57         br     %r1
  58 .L4:    .long  _GLOBAL_OFFSET_TABLE_-.L3
  59 #else
  60         al     %r1,.L4-.L3(%r1)     # load address of memmove
  61         br     %r1                  # jump to memmove
  62 .L4:    .long  memmove-.L3
  63 #endif
  64
  65 END(__bcopy)
  66
  67 #ifndef NO_WEAK_ALIAS
  68 weak_alias (__bcopy, bcopy)
  69 #endif