lib/sdk/crt/mem/i386/memmove_asm.s

   1 /*
   2  * void *memmove (void *to, const void *from, size_t count)
   3  *
   4  * NOTE: This code is duplicated in memcpy_asm.s
   5  */
   6
   7 .globl  _memmove
   8
   9 _memmove:
  10         push    %ebp
  11         mov     %esp,%ebp
  12
  13         push    %esi
  14         push    %edi
  15
  16         mov     8(%ebp),%edi
  17         mov     12(%ebp),%esi
  18         mov     16(%ebp),%ecx
  19
  20         cmp     %esi,%edi
  21         jbe     .CopyUp
  22         mov     %ecx,%eax
  23         add     %esi,%eax
  24         cmp     %eax,%edi
  25         jb      .CopyDown
  26
  27 .CopyUp:
  28         cld
  29
  30         cmp     $16,%ecx
  31         jb      .L1
  32         mov     %ecx,%edx
  33         test    $3,%edi
  34         je      .L2
  35 /*
  36  * Make the destination dword aligned
  37  */
  38         mov     %edi,%ecx
  39         and     $3,%ecx
  40         sub     $5,%ecx
  41         not     %ecx
  42         sub     %ecx,%edx
  43         rep     movsb
  44         mov     %edx,%ecx
  45 .L2:
  46         shr     $2,%ecx
  47         rep     movsl
  48         mov     %edx,%ecx
  49         and     $3,%ecx
  50 .L1:
  51         test    %ecx,%ecx
  52         je      .L3
  53         rep     movsb
  54 .L3:
  55         mov     8(%ebp),%eax
  56         pop     %edi
  57         pop     %esi
  58         leave
  59         ret
  60
  61 .CopyDown:
  62         std
  63
  64         add     %ecx,%edi
  65         add     %ecx,%esi
  66
  67         cmp     $16,%ecx
  68         jb      .L4
  69         mov     %ecx,%edx
  70         test    $3,%edi
  71         je      .L5
  72
  73 /*
  74  * Make the destination dword aligned
  75  */
  76         mov     %edi,%ecx
  77         and     $3,%ecx
  78         sub     %ecx,%edx
  79         dec     %esi
  80         dec     %edi
  81         rep     movsb
  82         mov     %edx,%ecx
  83
  84         sub     $3,%esi
  85         sub     $3,%edi
  86 .L6:
  87         shr     $2,%ecx
  88         rep     movsl
  89         mov     %edx,%ecx
  90         and     $3,%ecx
  91         je      .L7
  92         add     $3,%esi
  93         add     $3,%edi
  94 .L8:
  95         rep     movsb
  96 .L7:
  97         cld
  98         mov     8(%ebp),%eax
  99         pop     %edi
 100         pop     %esi
 101         leave
 102         ret
 103 .L5:
 104         sub     $4,%edi
 105         sub     $4,%esi
 106         jmp     .L6
 107
 108 .L4:
 109         test    %ecx,%ecx
 110         je      .L7
 111         dec     %esi
 112         dec     %edi
 113         jmp     .L8
 114