sysdeps/i386/i686/memcpy.S

   1 /* Copy memory block and return pointer to beginning of destination block
   2    For Intel 80x86, x>=6.
   3    This file is part of the GNU C Library.
   4    Copyright (C) 1999-2018 Free Software Foundation, Inc.
   5    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1999.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #include <sysdep.h>
  22 #include "asm-syntax.h"
  23
  24 #define PARMS   4               /* no space for saved regs */
  25 #define RTN     PARMS
  26 #define DEST    RTN
  27 #define SRC     DEST+4
  28 #define LEN     SRC+4
  29
  30         .text
  31 #if defined PIC && IS_IN (libc)
  32 ENTRY_CHK (__memcpy_chk)
  33         movl    12(%esp), %eax
  34         cmpl    %eax, 16(%esp)
  35         jb      HIDDEN_JUMPTARGET (__chk_fail)
  36 END_CHK (__memcpy_chk)
  37 #endif
  38 ENTRY (memcpy)
  39
  40         movl    %edi, %eax
  41         movl    DEST(%esp), %edi
  42         movl    %esi, %edx
  43         movl    SRC(%esp), %esi
  44
  45         movl    %edi, %ecx
  46         xorl    %esi, %ecx
  47         andl    $3, %ecx
  48         movl    LEN(%esp), %ecx
  49         cld
  50         jne     .Lunaligned
  51
  52         cmpl    $3, %ecx
  53         jbe     .Lunaligned
  54
  55         testl   $3, %esi
  56         je      1f
  57         movsb
  58         decl    %ecx
  59         testl   $3, %esi
  60         je      1f
  61         movsb
  62         decl    %ecx
  63         testl   $3, %esi
  64         je      1f
  65         movsb
  66         decl    %ecx
  67 1:      pushl   %eax
  68         movl    %ecx, %eax
  69         shrl    $2, %ecx
  70         andl    $3, %eax
  71         rep
  72         movsl
  73         movl    %eax, %ecx
  74         rep
  75         movsb
  76         popl    %eax
  77
  78 .Lend:  movl    %eax, %edi
  79         movl    %edx, %esi
  80         movl    DEST(%esp), %eax
  81
  82         ret
  83
  84         /* When we come here the pointers do not have the same
  85            alignment or the length is too short.  No need to optimize for
  86            aligned memory accesses. */
  87 .Lunaligned:
  88         shrl    $1, %ecx
  89         jnc     1f
  90         movsb
  91 1:      shrl    $1, %ecx
  92         jnc     2f
  93         movsw
  94 2:      rep
  95         movsl
  96         jmp     .Lend
  97 END (memcpy)
  98 libc_hidden_builtin_def (memcpy)