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

   1 /*
   2  * void *memcpy (void *to, const void *from, size_t count)
   3  *
   4  */
   5
   6 #include <asm.inc>
   7 #include <ks386.inc>
   8
   9 PUBLIC _memcpy
  10 PUBLIC _memmove
  11 .code
  12
  13 _memcpy:
  14 _memmove:
  15         push ebp
  16         mov ebp, esp
  17
  18         push esi
  19         push edi
  20
  21         mov     edi, [ebp + 8]
  22         mov     esi, [ebp + 12]
  23         mov     ecx, [ebp + 16]
  24
  25         cmp     edi, esi
  26         jbe     .CopyUp
  27         mov     eax, ecx
  28         add     eax, esi
  29         cmp     edi, eax
  30         jb .CopyDown
  31
  32 .CopyUp:
  33         cld
  34
  35         cmp     ecx, 16
  36         jb .L1
  37         mov edx, ecx
  38         test edi, 3
  39         je .L2
  40 /*
  41  * Make the destination dword aligned
  42  */
  43         mov ecx, edi
  44         and ecx, 3
  45         sub ecx, 5
  46         not ecx
  47         sub edx, ecx
  48         rep movsb
  49         mov ecx, edx
  50 .L2:
  51         shr ecx, 2
  52         rep movsd
  53         mov ecx, edx
  54         and ecx, 3
  55 .L1:
  56         test ecx, ecx
  57         je .L3
  58         rep movsb
  59 .L3:
  60         mov eax, [ebp + 8]
  61         pop edi
  62         pop esi
  63         leave
  64         ret
  65
  66 .CopyDown:
  67         std
  68
  69         add edi, ecx
  70         add esi, ecx
  71
  72         cmp ecx, 16
  73         jb .L4
  74         mov edx, ecx
  75         test edi, 3
  76         je .L5
  77
  78 /*
  79  * Make the destination dword aligned
  80  */
  81         mov ecx, edi
  82         and ecx, 3
  83         sub edx, ecx
  84         dec esi
  85         dec edi
  86         rep movsb
  87         mov ecx, edx
  88
  89         sub esi, 3
  90         sub edi, 3
  91 .L6:
  92         shr ecx, 2
  93         rep movsd
  94         mov ecx, edx
  95         and ecx, 3
  96         je .L7
  97         add esi, 3
  98         add edi, 3
  99 .L8:
 100         rep movsb
 101 .L7:
 102         cld
 103         mov eax, [ebp + 8]
 104         pop edi
 105         pop esi
 106         leave
 107         ret
 108 .L5:
 109         sub edi, 4
 110         sub esi, 4
 111         jmp .L6
 112
 113 .L4:
 114         test ecx, ecx
 115         je .L7
 116         dec esi
 117         dec edi
 118         jmp .L8
 119
 120 END