; * base on ntdll/rtl/mem.c v 1.13 2003/07/11 13:50:23 
; * 
; * COPYRIGHT:       See COPYING in the top level directory
; * PROJECT:         ReactOS kernel
; * FILE:            i386_RtlMemory.asm
; * PURPOSE:         Memory functions
; * PROGRAMMER:      Magnus Olsen (magnusolsen@greatlord.com)
; * UPDATE HISTORY:
; *                  Created 20/07-2003
; * 
  

	  BITS 32
        GLOBAL _RtlMoveMemory@12   ; (no bug) (max optimze code) 
            
	  SECTION .text

; * 
; * [1] VOID STDCALL RtlMoveMemory (PVOID Destination, CONST VOID *Source,ULONG Length);
; * 



_RtlMoveMemory@12:
      mov ecx,dword [esp + 12 ]              ; ecx = Length                                       
	cmp ecx,0                              ; if (Length==0) goto .zero
	je  .zero	        
      
      pushad
      mov edi, dword [esp + (4 + 32)]        ; eax = Destination                       
      mov esi, dword [esp + (8 + 32)]        ; edx = Source	                                

; calc how many bytes it should handle same time
      mov ebx,ecx                            ; temp_Length = Length                  
      shr ecx,2                              ; Length = Length / sizeof(ULONG)      
      jz .1byte                              ; if (Length==0) goto .1byte
       
      shl ecx,2                              ; Length = Length * sizeof(ULONG)      
      sub ebx,ecx                            ; temp_Length = temp_Length - Length
      jz .4bytes                             ; if (temp_Length==0) goto .4byte

; move 4byte and 1byte
      shr ecx,2                              ; Length = Length  / sizeof(ULONG)        
      cld                                    ; clear d flag
      rep movsd                              ; while (Length!=0) { (ULONG *) Destination[Length-1] = (ULONG *) Source[Length-1]; Legnth = Legnth - 1 }
      mov ecx,ebx                            ; Length = temp_Length  
      rep movsb                              ; while (Length!=0) { (UCHAR *) Destination[Length-1] = (UCHAR *) Source[Length-1]; Legnth = Legnth - 1 }
      popad                                  ; restore regiester
      ret 12                                 ; return  
      
; move 1byte            
.1byte:   
       mov ecx,dword [esp + (12 +32) ]       ; ecx = Length                                               
       cld                                   ; clear d flag
       rep movsb                             ; while (Length!=0) { (UCHAR *) Destination[Length-1] = (UCHAR *) Source[Length-1]; Legnth = Legnth - 1 }

       popad                                 ; restore regiester
       ret 12                                ; return

; move 4bytes     
.4bytes:
       shr ecx,2                             ; Length = Length  / sizeof(ULONG)         
       cld                                   ; clear d flag
       rep movsd                             ; while (Length!=0) { (ULONG *) Destination[Length-1] = (ULONG *) Source[Length-1]; Legnth = Legnth - 1 }
       popad                                 ; restore regiester
.zero:	           	
       ret 12                                ; return