Where is CopyMemory?

[SamLe]

First I called to ZeroMemory and the assembler said Undefined Symbol so i used RtlZeroMemory instead. It worked correctly but CopyMemory didn't though i used Rtl, the assembler always said "undefined symbol". I know that all path defined correctly, i still don't know how to use CopyMemory in MASM32!

[Mark Jones]

Hi SamLe, have you tried RtlCopyMemory? It looks like the equates for "CopyMemory" in \masm32\include\Windows.inc have been disabled. (There must be a good reason for this.)

If you just need to copy some memory, there are many simple (and not-so-simple) algorithms that will work. Try a search at the top-left of the page.

Note that "CopyMemory" appears to be defined in the GoASM v2.0 headers. (I cannot test this at the moment.)

[ToutEnMasm]

Hello,
RtlZeroMemory is in kernel32

ZeroMemory   equ   < RtlZeroMemory>

[Vortex]

Hi SamLe,

Also, have a look at the Masm32 library function MemCopy :

Code Select Expand

MemCopy

MemCopy proc public uses esi edi Source:PTR BYTE,Dest:PTR BYTE,ln:DWORD

Note here that the source and destination parameters are DWORD size addresses of the respective source and destination buffers.

Parameters

1. Source Source buffer address.
2. Dest Destination buffer address.
3. ln The number of bytes to copy.

Return Value

There is no return value.

Comments

The destination buffer must be at least the same size as the source buffer otherwise the procedure will write past the end of the destination buffer and cause a write page fault.

Example

invoke MemCopy,ADDR MySource,ADDR MyDest,ln
MemCopy copies the byte count of memory from a source buffer to a destination buffer.


[peaslee]

Does this mean anything?

http://www.theregister.co.uk/2009/05/15/microsoft_banishes_memcpy/

[PBrennick]

 ... or in GeneSys:

Code Select Expand


OPTION PROLOGUE:NONE
OPTION EPILOGUE:NONE

CopyMemory proc pDest:dword, pSrc:dword, dwCount:dword
    mov edx,edi
    mov ecx,[esp+3*4];dwCount
    mov eax,esi
    mov edi,[esp+1*4];pDest             
    shr ecx,2
    mov esi,[esp+2*4];pSrc
    rep movsd       
    mov ecx,[esp+3*4];dwCount
    and ecx,3
    jnz @F
    mov esi,eax
    mov edi,edx
    ret 3*4
@@: rep movsb       
    mov esi,eax
    mov edi,edx
    ret 3*4
CopyMemory

OPTION PROLOGUE:PROLOGUEDEF
OPTION EPILOGUE:EPILOGUEDEF


Paul

[GregL]

CopyMemory is defined as follows in winbase.h:

    #define CopyMemory RtlCopyMemory

So, just use RtlCopyMemory in MASM.

[SamLe]

Thank everybody so much, i got it. :U

[Vortex]

Another one in the GeneSys project :

Code Select Expand

\GeneSys\GeneSysLib\copymem.asm

[Larry Hammick]

MoveMemory, which appears in various dll's under various names, is a good substitute for CopyMemory. From Microsoft:

VOID MoveMemory (
    PVOID Destination,   // address of move destination
    CONST VOID *Source,   // address of block to move
    DWORD Length    // size, in bytes, of block to move
   );   

Parameters
Destination -- Points to the starting address of the destination of the move.
Source -- Points to the starting address of the block of memory to move.
Length -- Specifies the size, in bytes, of the block of memory to move.

This function has no return value.

The source and destination blocks may overlap.

-----
or you can roll your own:

Code Select Expand

movememory proc uses esi edi to:dword,from:dword,amt:dword
    mov ecx,amt    ;returns ecx=0 if from<to, else ecx=-1.
    mov esi,from
    mov edi,to
    cmp esi,edi
    jc  short work_downwards
    rep movsb
    jmp short movememory_ret
work_downwards:
    dec ecx
    js  short movememory_ret
    mov al,[esi+ecx]
    mov [edi+ecx],al
    jmp short work_downwards
movememory_ret:
    ret
movememory endp

[MichaelW]

Judging from what I see in the WinNT.h from the PSDK, on 32-bit systems you are actually calling the CRT memmove or memcpy functions. The attachment contains a cycle-count test. Typical results on a P3:

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228 cycles, RtlMoveMemory
229 cycles, memmove
229 cycles, memcpy
1301 cycles, movememory

228 cycles, RtlMoveMemory
229 cycles, memmove
229 cycles, memcpy
1301 cycles, movememory

228 cycles, RtlMoveMemory
228 cycles, memmove
229 cycles, memcpy
1312 cycles, movememory


[jj2007]

Celeron M:

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149 cycles, RtlMoveMemory
143 cycles, memmove
143 cycles, memcpy
537 cycles, movememory

[hutch--]

From the years of people playing with these, the API calls are low on the rank of useful, they work but do nothing that hand coded cannot do better from simple byte level copy to SSE2+ versions with the special case circuitry for REP MOVS? hitting somewhere in the middle.

[KSS]

AMD Athlon 64 X2 DualCore 4600+ (overclocked up to 2676.0 MHz)

Code Select Expand

90 cycles, RtlMoveMemory
104 cycles, memmove
100 cycles, memcpy
794 cycles, movememory

[oex]

89 cycles, RtlMoveMemory
90 cycles, memmove
90 cycles, memcpy
784 cycles, movememory

89 cycles, RtlMoveMemory
90 cycles, memmove
90 cycles, memcpy
784 cycles, movememory

89 cycles, RtlMoveMemory
90 cycles, memmove
90 cycles, memcpy
784 cycles, movememory

Press any key to exit...

Sempron 3100+