前些日子在一个POWER BASIC的群里跟人讨论的时候，大家对PB能够内嵌汇编很感兴趣，然后有人问我能不能写一个CopyMemory出来，跟WIN32提供的那个比比看，效率怎么样
当时我认为，肯定是自己写的快，理由是WIN32的那个虽然是由kernel32.dll引出，但是真正的代码却是在NTDLL中。

正在装载数据……

这样调用起来，开销一定会大好多。于是就写了一个，用VB调，循环一千次。没想到比WIN32提供的那个慢了一倍多。不知道是编译器还是代码的问题

'---------------------------------代码-------------------------------------
'*********************************************************
'
'                    文件名:  copymemory.bas
'                      作者  :  money
'                    E-mail:  2258773@163.com
'
'*********************************************************

#COMPILE DLL
#DIM ALL

'VB调用声明
'PRIVATE DECLARE SUB CopyMemoryLIB "copymemory.dll" ALIAS "CopyMemory" (dest AS ANY, sure AS ANY, BYVAL Lenght AS LONG)

FUNCTION LIBMAIN(BYVAL hInstance AS DWORD, _
                 BYVAL lReason   AS LONG, _
                 BYVAL lReserved AS LONG) AS LONG

    LIBMAIN=1

END FUNCTION

'====================================================================
'VB调用声明
'PRIVATE DECLARE SUB CopyMemoryLIB "copymemory2.dll" ALIAS "CopyMemory" (dest AS ANY, sure AS ANY, BYVAL Lenght AS LONG)
'====================================================================
SUB CopyMemory ALIAS "CopyMemory"(dest AS DWORD,sure AS DWORD,BYVAL Lenght AS DWORD)EXPORT

    !cld

    !mov ecx,lenght
    !mov esi,sure
    !mov edi,dest

    !test ecx,&H3
    !jz SD

    !test ecx,&H1
    !jz SW

SD:
    !shr ecx,2
    !rep movsd

    EXIT SUB
SW:
    !shr ecx,1
    !rep movsw

    EXIT SUB

    !rep movsb

END SUB
'---------------------------------代码------------------------------------- 

本文来源：http://blog.csdn.net/lorl2/archive/2007/08/26/1759608.aspx