kernel/eka/common/win32/cmem.cpp
changeset 247 d8d70de2bd36
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/kernel/eka/common/win32/cmem.cpp	Wed Aug 18 11:08:29 2010 +0300
@@ -0,0 +1,142 @@
+// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// e32\common\win32\cmem.cpp
+//
+//
+
+#include "common.h"
+
+#ifdef __MEMMOVE_MACHINE_CODED__
+
+extern "C" {
+
+// See header file e32cmn.h for the in-source documentation.
+EXPORT_C __NAKED__ TAny* memmove(TAny* , const TAny* , unsigned int)
+	{
+	_asm push      ebx							; // Save used registers
+	_asm push      esi
+	_asm push      edi
+	_asm push      ebp
+
+	_asm cmp       dword ptr [esp+0x1c],0x0		; // Is aLength == 0?
+	_asm mov       eax,dword ptr [esp+0x14]		; // Ptr to destination
+	_asm mov       ebx,dword ptr [esp+0x18]		; // Ptr to source
+	_asm je        End							; // aLength is 0, just return
+
+	_asm mov       ecx,eax						; // Copy destination
+	_asm xor       ebp,ebp						; // ebp = 0
+	_asm test      ecx,0x3						; // Dest word aligned?
+	_asm mov       edx,ebx						; // Copy ptr to source
+	_asm jne       Misaligned					; // No
+	_asm test      edx,0x3						; // Source word aligned?
+	_asm jne       Misaligned					; // No
+	_asm mov       ebp,dword ptr [esp+0x1c]		; // ebp = aLength
+	_asm shr       ebp,0x2						; // ebp = aLength in words
+
+Misaligned:
+
+	_asm lea       edx,dword ptr [ebp*4+0x0]	; // edx = aLength in words
+	_asm sal       ebp,0x2						; // ebp = aLength in bytes
+	_asm add       ebp,ecx						; // Point to end of destination
+	_asm mov       edi,dword ptr [esp+0x1c]		; // Get number of bytes to copy
+	_asm sub       edi,edx						; // Find remainder (aLength % 3)
+	_asm cmp       eax,ebx						; // Dest >= source?
+	_asm mov       edx,ebp						; // Ptr to end of destination
+	_asm jae       DoDescendingCopy				; // Yes, copy downwards
+
+	_asm jmp       AscendingCopy				; // No, copy upwards
+
+AscendingCopyLoop:
+
+	_asm mov       ebp,dword ptr [ebx]			; // Get a word
+	_asm mov       dword ptr [ecx],ebp			; // And store it
+	_asm add       ebx,0x4						; // Increment source by a word
+	_asm add       ecx,0x4						; // Increment destination by a word
+
+AscendingCopy:
+
+	_asm cmp       ecx,edx						; // Still data to copy?
+	_asm jb        AscendingCopyLoop			; // Yes
+
+	_asm mov       ebp,eax						; // Copy ptr to destination
+	_asm add       ebp,dword ptr [esp+0x1c]		; // Point to end of destination
+	_asm jmp       CopyRemainder				; // Copy left over (aLength % 3) bytes
+
+CopyRemainderLoop:
+
+	_asm movzx     edx,byte ptr [ebx]			; // Get a byte
+	_asm mov       byte ptr [ecx],dl			; // And store it
+	_asm inc       ebx							; // Increment source by a byte
+	_asm inc       ecx							; // Increment destination by a byte
+
+CopyRemainder:
+
+	_asm cmp       ecx,ebp						; // Any remaining bytes to copy?
+	_asm jb        CopyRemainderLoop			; // Yes, go do it
+
+	_asm jmp       End							; // All done
+
+DoDescendingCopy:
+
+	_asm cmp       eax,ebx						; // Still data to copy?
+	_asm jbe       End							; // No, all done
+
+	_asm lea       esi,dword ptr [edi+ebp]		; // Get ptr to end of destination
+	_asm mov       edi,ebx						; // Get ptr to source
+	_asm add       edi,dword ptr [esp+0x1c]		; // Point to end of source
+	_asm jmp       DescendingCopyRemainder		; // Copy copy some data
+
+DescendingCopyRemainderLoop:
+
+	_asm dec       edi							; // Decrement source by a byte
+	_asm dec       esi							; // Decrement dest by a byte
+	_asm movzx     ebx,byte ptr [edi]			; // Get a byte
+	_asm mov       byte ptr [esi],bl			; // And store it
+
+DescendingCopyRemainder:
+
+	_asm cmp       esi,ebp						; // Still data to copy?
+	_asm ja        DescendingCopyRemainderLoop	; // Yes, go do it
+
+	_asm jmp       DescendingCopy				; // Go copy the bulk of the data
+
+DescendingCopyLoop:
+
+	_asm sub       edi,0x4						; // Decrement source by a word
+	_asm sub       edx,0x4						; // Decrement dest by a word
+	_asm mov       ebx,dword ptr [edi]			; // Get a word
+	_asm mov       dword ptr [edx],ebx			; // And store it
+
+DescendingCopy:
+
+	_asm cmp       edx,ecx						; // Still data to copy
+	_asm ja        DescendingCopyLoop			; // Yes, go do it
+
+End:
+
+	_asm pop       ebp							; // Restore used registers
+	_asm pop       edi
+	_asm pop       esi
+	_asm pop       ebx
+	_asm ret
+	}
+
+// See header file e32cmn.h for the in-source documentation.
+EXPORT_C __NAKED__ TAny* memcpy(TAny* , const TAny* , unsigned int)
+	{
+	__asm jmp (memmove);						; // memmove() will perform the same function
+	}
+}
+
+#endif // defined(__MEMMOVE_MACHINE_CODED__)