昨晚用MASM寫了個內存比較的函數(DLL供VC/VB調用)

用MASM編寫的兩段內存比較函數。提供源碼及SDK和VB6示範代碼。不知哪位高手能打造個更高效的方法? :) 請send: [email protected], 共討論之. thanks very much.

; 兩段內存比較函數。
MMemCmpi proc uses esi edi ebx pDst:DWORD, pSrc:DWORD, nLength:DWORD
   
    mov     esi, DWORD ptr [pSrc]
    mov     edi, DWORD ptr [pDst]
   
    ; argument check
    test    esi, esi
    jz      @Exit
    test    edi, edi
    jz      @Exit
   
    cld   
    mov     ecx, DWORD ptr [nLength]
    mov     ebx, ecx
   
    shr     ecx, 2
    repz    cmpsd
  JNZ  @Exit
 
    mov     ecx, edx
    and     ecx, 3
    repz    cmpsb
    JZ  @Same
   
 @Exit:
   XOR  EAX, EAX
   NOT  EAX
    ret
 
 @Same:
   XOR  EAX, EAX
    ret
   
MMemCmpi endp

演示：如果pSrc,pDst兩段內存相同就返回0，否則為非零。如下測試代碼：

SDK 代碼：
/*===============================================================================================================*/
#include "windows.h"
#include "tchar.h"

#ifdef __cplusplus
#define EXPORT extern "C" __declspec(dllexport)
#else
#define EXPORT __declspec(dllexport)
#endif

EXPORT BOOL MMemCmpi( LPVOID pDst, LPVOID pSrc, UINT nLength );

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR    lpCmdLine,
                     int       nCmdShow)
{
    RECT rc1, rc2;
    BOOL fResult = 0;
    TCHAR szText[MAX_PATH] = TEXT("/0");

 UNREFERENCED_PARAMETER(hPrevInstance);
 UNREFERENCED_PARAMETER(lpCmdLine);

    SetRect(&rc1, 5, 6, 7, 8);
    SetRect(&rc2, 5, 6, 7, 8);

    fResult = MMemCmpi( &rc1, &rc2, sizeof(rc1) );
    wsprintf( szText, TEXT("test equal to: %i/n"), fResult );
    MessageBox( NULL, szText, _T(""), MB_OK );

    rc1.left = 200;

    fResult = MMemCmpi( &rc1, &rc2, sizeof(rc1) );
    wsprintf( szText, TEXT("not equal to: %i/n"), fResult );
    MessageBox( NULL, szText, _T(""), MB_OK );

 return 0;
}
/*===============================================================================================================*/

VB6代碼：
/*===============================================================================================================*/

'Rectangle
Type RECT
    Left                        As Long
    Top                         As Long
    Right                       As Long
    Bottom                      As Long
End Type
 
Declare Function MMemCmpi Lib "Utils.dll" _
   (ByVal pDst As Long, _
    ByVal pSrc As Long, _
    ByVal nLength As Long) As Long

public sub Main()

    dim rc1 as RECT
    dim rc2 as RECT

    SetRect(rc1, 5, 6, 7, 8);
    SetRect(rc2, 5, 6, 7, 8);

    MsgBox "test the equal to: " & MMemCmpi( varptr(rc1), varptr(rc2), lenb(rc1) )

    rc1.left = 200

    MsgBox "test the not equal to: " & MMemCmpi( varptr(rc1), varptr(rc2), lenb(rc1) )

end sub
/*===============================================================================================================*/