lib/ntdll/nasm/rtl/i386_RtlMoveMemory.asm

   1 ; * base on ntdll/rtl/mem.c v 1.13 2003/07/11 13:50:23
   2 ; *
   3 ; * COPYRIGHT:       See COPYING in the top level directory
   4 ; * PROJECT:         ReactOS kernel
   5 ; * FILE:            i386_RtlMemory.asm
   6 ; * PURPOSE:         Memory functions
   7 ; * PROGRAMMER:      Magnus Olsen (magnusolsen@greatlord.com)
   8 ; * UPDATE HISTORY:
   9 ; *                  Created 20/07-2003
  10 ; *
  11
  12
  13           BITS 32
  14         GLOBAL _RtlMoveMemory@12   ; (no bug) (max optimze code)
  15
  16           SECTION .text
  17
  18 ; *
  19 ; * [1] VOID STDCALL RtlMoveMemory (PVOID Destination, CONST VOID *Source,ULONG Length);
  20 ; *
  21
  22
  23
  24 _RtlMoveMemory@12:
  25       mov ecx,dword [esp + 12 ]              ; ecx = Length
  26         cmp ecx,0                              ; if (Length==0) goto .zero
  27         je  .zero
  28
  29       pushad
  30       mov edi, dword [esp + (4 + 32)]        ; eax = Destination
  31       mov esi, dword [esp + (8 + 32)]        ; edx = Source
  32
  33 ; calc how many bytes it should handle same time
  34       mov ebx,ecx                            ; temp_Length = Length
  35       shr ecx,2                              ; Length = Length / sizeof(ULONG)
  36       jz .1byte                              ; if (Length==0) goto .1byte
  37
  38       shl ecx,2                              ; Length = Length * sizeof(ULONG)
  39       sub ebx,ecx                            ; temp_Length = temp_Length - Length
  40       jz .4bytes                             ; if (temp_Length==0) goto .4byte
  41
  42 ; move 4byte and 1byte
  43       shr ecx,2                              ; Length = Length  / sizeof(ULONG)
  44       cld                                    ; clear d flag
  45       rep movsd                              ; while (Length!=0) { (ULONG *) Destination[Length-1] = (ULONG *) Source[Length-1]; Legnth = Legnth - 1 }
  46       mov ecx,ebx                            ; Length = temp_Length
  47       rep movsb                              ; while (Length!=0) { (UCHAR *) Destination[Length-1] = (UCHAR *) Source[Length-1]; Legnth = Legnth - 1 }
  48       popad                                  ; restore regiester
  49       ret 12                                 ; return
  50
  51 ; move 1byte
  52 .1byte:
  53        mov ecx,dword [esp + (12 +32) ]       ; ecx = Length
  54        cld                                   ; clear d flag
  55        rep movsb                             ; while (Length!=0) { (UCHAR *) Destination[Length-1] = (UCHAR *) Source[Length-1]; Legnth = Legnth - 1 }
  56
  57        popad                                 ; restore regiester
  58        ret 12                                ; return
  59
  60 ; move 4bytes
  61 .4bytes:
  62        shr ecx,2                             ; Length = Length  / sizeof(ULONG)
  63        cld                                   ; clear d flag
  64        rep movsd                             ; while (Length!=0) { (ULONG *) Destination[Length-1] = (ULONG *) Source[Length-1]; Legnth = Legnth - 1 }
  65        popad                                 ; restore regiester
  66 .zero:
  67        ret 12                                ; return
  68
  69