tut35.html

WINDOWS程序员使用指南--汇编基础

<p><font face="Tahoma" size="-1">Pass the words, the memory block handle, the 
  size of the data read from wordfile.txt, the address of the color dword that 
  will be used to hilight the words and the address of <font color="#0000CC"><b>ASMSyntaxArray</b></font>.</font></p>
<p><font face="Tahoma" size="-1">Now, let's examine what <font color="#0000CC"><b>ParseBuffer</b></font> 
  does. In essence, this function accepts the buffer containing the words to be 
  hilighted ,parses them to individual words and stores each of them in a <font color="#006666"><b>WORDINFO</b></font> 
  structure array that can be accessed quickly from <font color="#006666"><b>ASMSyntaxArray</b></font>.</font><font face="Tahoma"><b> 
  <br>
  </b></font></p>
<pre><font face="Tahoma"><b>ParseBuffer proc uses edi esi hHeap:DWORD,pBuffer:DWORD, nSize:DWORD, ArrayOffset:DWORD,pArray:DWORD
	LOCAL buffer[128]:BYTE
	LOCAL InProgress:DWORD
	mov InProgress,FALSE</b></font></pre>
<p><font face="Tahoma"><font size="-1">InProgress is the flag I use to indicate 
  whether the scanning process has begun. If the value is FALSE, we haven't encountered 
  a non-white space character yet.</font><b><br>
  </b></font></p>
<pre><font face="Tahoma"><b>	lea esi,buffer	
	mov edi,pBuffer
	invoke CharLower,edi</b></font></pre>
<p><font face="Tahoma"><font size="-1">esi points to our local buffer that will 
  contain the word we have parsed from the word list. edi points to the word list 
  string. To simplify the search later, we convert all characters to lowercase.</font><b><br>
  </b></font></p>
<pre><font face="Tahoma"><b>	mov ecx,nSize			
SearchLoop:
	or ecx,ecx
	jz Finished
	cmp byte ptr [edi]," "
	je EndOfWord
	cmp byte ptr [edi],9 	; tab
	je EndOfWord</b></font></pre>
<p><font face="Tahoma"><font size="-1">Scan the whole word list in the buffer, 
  looking for the white spaces. If a white space is found, we have to determine 
  whether it marks the end or the beginning of a word.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>	mov InProgress,TRUE
	mov al,byte ptr [edi]
	mov byte ptr [esi],al
	inc esi</b></font>
<font face="Tahoma"><b>SkipIt:
	inc edi
	dec ecx
	jmp SearchLoop</b></font></pre>
<p><font face="Tahoma"><font face="Tahoma"><font size="-1">If the byte under scrutiny 
  is not a white space, we copy it to the buffer to construct a word and then 
  continue the scan.</font></font><b> </b></font></p>
<pre><font face="Tahoma"><b>EndOfWord:
	cmp InProgress,TRUE
	je WordFound
	jmp SkipIt</b></font></pre>
<p><font face="Tahoma"><font size="-1">If a white space is found, we check the 
  value in <font color="#006666"><b>InProgress</b></font>. If the value is TRUE, 
  we can assume that the white space marks the end of a word and we may proceed 
  to put the word currently in the local buffer (pointed to by esi) into a <font color="#006666"><b>WORDINFO</b></font> 
  structure. If the value is FALSE, we continue the scan until a non-white space 
  character is found. </font><b> </b></font></p>
<pre><font face="Tahoma"><b>WordFound:
	mov byte ptr [esi],0
	push ecx
	invoke HeapAlloc,hHeap,HEAP_ZERO_MEMORY,sizeof WORDINFO</b></font></pre>
<p><font face="Tahoma"><font size="-1">When the end of a word is found, we append 
  0 to the buffer to make the word an ASCIIZ string. We then allocate a block 
  of memory from the heap the size of <font color="#006666"><b>WORDINFO</b></font> 
  for this word.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>	push esi
	mov esi,eax
	assume esi:ptr WORDINFO
	invoke lstrlen,addr buffer
	mov [esi].WordLen,eax</b></font></pre>
<p><font face="Tahoma"><font size="-1">We obtain the length of the word in the 
  local buffer and store it in the <font color="#006666"><b>WordLen</b></font> 
  member of the <font color="#006666"><b>WORDINFO</b></font> structure, to be 
  used as a quick comparison.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>	push ArrayOffset
	pop [esi].pColor</b></font></pre>
<p><font face="Tahoma"><font size="-1">Store the address of the dword that contains 
  the color to be used to hilight the word in <font color="#006666"><b>pColor</b></font> 
  member.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>	inc eax
	invoke HeapAlloc,hHeap,HEAP_ZERO_MEMORY,eax
	mov [esi].pszWord,eax
	mov edx,eax
	invoke lstrcpy,edx,addr buffer</b></font></pre>
<p><font face="Tahoma"><font size="-1">Allocate memory from the heap to store 
  the word itself. Right now, the <font color="#006666"><b>WORDINFO</b></font> 
  structure is ready to be inserted into the appropriate linked list.</font><b> 
  </b></font></p>
<pre><font face="Tahoma"><b>	mov eax,pArray
	movzx edx,byte ptr [buffer]
	shl edx,2		; multiply by 4
	add eax,edx</b></font></pre>
<p><font face="Tahoma"><font size="-1">pArray contains the address of <font color="#006666"><b>ASMSyntaxArray</b></font>. 
  We want to move to the dword that has the same index as the value of the first 
  character of the word. So we put the first character of the word in edx then 
  multiply edx by 4 (because each element in <font color="#006666"><b>ASMSyntaxArray</b></font> 
  is 4 bytes in size) and then add the offset to the address of <font color="#006666"><b>ASMSyntaxArray</b></font>. 
  We have the address of the corresponding dword in eax.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>	.if dword ptr [eax]==0
		mov dword ptr [eax],esi
	.else
		push dword ptr [eax]
		pop [esi].NextLink
		mov dword ptr [eax],esi
	.endif</b></font></pre>
<p><font face="Tahoma"><font size="-1">Check the value of the dword. If it's 0, 
  it means there is currently no word that begins with this character in the list. 
  We thus put the address of the current <font color="#006666"><b>WORDINFO</b></font> 
  structure in that dword.</font></font></p>
<p><font face="Tahoma"><font size="-1">If the value in the dword is not 0, it 
  means there is at least one word that begins with this character in the array. 
  We thus insert this <font color="#006666"><b>WORDINFO</b></font> structure to 
  the head of the linked list and update its NextLink member to point to the next 
  <font color="#006666"> <b>WORDINFO</b></font> structure.</font></font></p>
<pre><font face="Tahoma"><b>	pop esi
	pop ecx
	lea esi,buffer
	mov InProgress,FALSE
	jmp SkipIt</b></font></pre>
<p><font face="Tahoma"><font size="-1">After the operation is complete, we begin 
  the next scan cycle until the end of buffer is reached. </font></font></p>
<pre><font face="Tahoma"><b>		invoke SendMessage,hwndRichEdit,EM_SETTYPOGRAPHYOPTIONS,TO_SIMPLELINEBREAK,TO_SIMPLELINEBREAK
		invoke SendMessage,hwndRichEdit,EM_GETTYPOGRAPHYOPTIONS,1,1
		.if eax==0		; means this message is not processed
			mov RichEditVersion,2
		.else
			mov RichEditVersion,3
			invoke SendMessage,hwndRichEdit,EM_SETEDITSTYLE,SES_EMULATESYSEDIT,SES_EMULATESYSEDIT
		.endif</b></font></pre>
<p><font face="Tahoma" size="-1">After the richedit control is created, we need 
  to determine the its version. This step is necessary since <font color="#006666"><b>EM_POSFROMCHAR</b></font> 
  behaves differently for RichEdit 2.0 and 3.0 and <font color="#006666"><b>EM_POSFROMCHAR</b></font> 
  is crucial to our syntax hilighting routine. I have never seen a documented 
  way of checking the version of richedit control thus I have to use a workaround. 
  In this case, I set an option that is specific to version 3.0 and immediately 
  retrieve its value. If I can retrieve the value, I assume that the control version 
  is 3.0.</font></p>
<p><font face="Tahoma" size="-1">If you use RichEdit control version 3.0, you 
  will notice that updating the font color for a large file takes quite a long 
  time. This problem seems to be specific to version 3.0. I found a workaround: 
  making the control emulate the behavior of the system edit control by sending 
  <font color="#006666"> <b>EM_SETEDITSTYLE</b></font> message.</font></p>
<p><font face="Tahoma" size="-1">After we can obtain the version information, 
  we proceed to subclass the richedit control. We will now examine the new window 
  procedure for the richedit control.</font></p>
<pre><font face="Tahoma"><b>NewRichEditProc proc hWnd:DWORD, uMsg:DWORD, wParam:DWORD, lParam:DWORD
	........
	.......
	.if uMsg==WM_PAINT
		push edi
		push esi
		invoke HideCaret,hWnd
		invoke CallWindowProc,OldWndProc,hWnd,uMsg,wParam,lParam
		push eax</b></font></pre>
<p><font face="Tahoma"><font size="-1">We handle <font color="#006666"><b>WM_PAINT</b></font> 
  message. First, we hide the caret so as to avoid some ugly gfx after the hilighting. 
  After that we pass the message to the original richedit procedure to let it 
  update the window. When <font color="#006666"><b>CallWindowProc</b></font> returns, 
  the text is updated with its usual color/background. Now is our opportunity 
  to do syntax hilighting.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>		mov edi,offset ASMSyntaxArray
		invoke GetDC,hWnd
		mov hdc,eax
		invoke SetBkMode,hdc,TRANSPARENT</b></font></pre>
<p><font face="Tahoma"><font size="-1">Store the address of ASMSyntaxArray in 
  edi. Then we obtain the handle to the device context and set the text background 
  mode to transparent so the text that we will write will use the default background 
  color. </font><b> <br>
  </b></font></p>
<pre><font face="Tahoma"><b>		invoke SendMessage,hWnd,EM_GETRECT,0,addr rect
		invoke SendMessage,hWnd,EM_CHARFROMPOS,0,addr rect
		invoke SendMessage,hWnd,EM_LINEFROMCHAR,eax,0
		invoke SendMessage,hWnd,EM_LINEINDEX,eax,0</b></font></pre>
<p><font face="Tahoma"><font size="-1">We want to obtain the visible text so we 
  first have to obtain the formatting rectangle by sending <font color="#006666"><b>EM_GETRECT</b></font> 
  message to the richedit control. Now that we have the bounding rectangle, we 
  obtain the nearest character index to the upper left corner of the rectangle 
  with <font color="#006666"><b>EM_CHARFROMPOS</b></font>. Once we have the character 
  index (the first visible character in the control), we can start to do syntax 
  hilighting starting from that position. But the effect might not be as good 
  as when we start from the first character of the line that the character is 
  in. That's why I need to obtain the line number of that the first visible character 
  is in by sending <font color="#006666"><b>EM_LINEFROMCHAR</b></font> message. 
  To obtain the first character of that line, I send <font color="#006666"><b>EM_LINEINDEX</b></font> 
  message.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>		mov txtrange.chrg.cpMin,eax
		mov FirstChar,eax
		invoke SendMessage,hWnd,EM_CHARFROMPOS,0,addr rect.right
		mov txtrange.chrg.cpMax,eax</b></font></pre>
<p><font face="Tahoma"><font size="-1">Once we have the first character index, 
  store it for future reference in FirstChar variable. Next we obtain the last 
  visible character index by sending <font color="#006666"><b>EM_CHARFROMPOS</b></font>, 
  passing the lower-right corner of the formatting rectangle in <font color="#0000CC"><b>lParam</b></font>.</font><b> 
  </b></font></p>
<pre><font face="Tahoma"><b>		push rect.left
		pop RealRect.left
		push rect.top
		pop RealRect.top
		push rect.right
		pop RealRect.right
		push rect.bottom
		pop RealRect.bottom
		invoke CreateRectRgn,RealRect.left,RealRect.top,RealRect.right,RealRect.bottom
		mov hRgn,eax
		invoke SelectObject,hdc,hRgn
		mov hOldRgn,eax</b></font></pre>
<p><font face="Tahoma"><font size="-1">While doing syntax hilighting, I noticed 
  an unsightly side-effect of this method: if the richedit control has a margin 
  (you can specify margin by sending <font color="#006666"><b>EM_SETMARGINS</b></font> 
  message to the richedit control), <font color="#006666"><b>DrawText</b></font> 
  writes over the margin. Thus I need to create a clipping region, the size of 
  the formatting rectangle, by calling <font color="#006666"><b>CreateRectRgn</b></font>. 
  The output of GDI functions will be clipped to the &quot;writable&quot; area.</font></font></p>
<p><font face="Tahoma" size="-1">Next, we need to hilight the comments first and 
  get them out of our way. My method is to search for &quot;;&quot; and hilight 
  the text with the comment color until the carriage return is found. I will not 
  analyze the routine here: it's fairly long and complicated. Suffice here to 
  say that, when all the comments are hilighted, we replace them with 0s in the 
  buffer so that the words in the comments will not be processed/hilighted later.</font></p>
<pre><font face="Tahoma"><b>		mov ecx,BufferSize
		lea esi,buffer
		.while ecx>0
			mov al,byte ptr [esi]
			.if al==" " || al==0Dh || al=="/" || al=="," || al=="|" || al=="+" || al=="-" || al=="*" || al=="&" || al=="<" || al==">" || al=="=" || al=="(" || al==")" || al=="{" || al=="}" || al=="[" || al=="]" || al=="^" || al==":" || al==9
				mov byte ptr [esi],0
			.endif
			dec ecx
			inc esi
		.endw</b></font></pre>
<p><font face="Tahoma"><font size="-1">Once the comments are out of our way, we 
  separate the words in the buffer by replacing the &quot;separator&quot; characters 
  with 0s. With this method, we need not concern about the separator characters 
  while processing the words in the buffer anymore: there is only one separator 
  character, NULL.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>		lea esi,buffer
		mov ecx,BufferSize
		.while ecx>0
			mov al,byte ptr [esi]
			.if al!=0</b></font></pre>
<p><font face="Tahoma"><font size="-1">Search the buffer for the first character 
  that is not null,ie, the first character of a word.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>				push ecx
				invoke lstrlen,esi
				push eax
				mov edx,eax</b></font></pre>
<p><font face="Tahoma"><font size="-1">Obtain the length of the word and put it 
  in edx </font><b> </b></font></p>
<pre><font face="Tahoma"><b>				movzx eax,byte ptr [esi]
				.if al>="A" && al<="Z"
					sub al,"A"
					add al,"a"
				.endif</b></font></pre>
<p><font face="Tahoma"><font size="-1">Convert the character to lowercase (if 
  it's an uppercase character)</font><b> </b></font></p>
<pre><font face="Tahoma"><b>				shl eax,2
				add eax,edi		; edi contains the pointer to the WORDINFO pointer array
				.if dword ptr [eax]!=0</b></font></pre>
<p><font face="Tahoma"><font size="-1">After that, we skip to the corresponding 
  dword in ASMSyntaxArray and check whether the value in that dword is 0. If it 
  is, we can skip to the next word.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>					mov eax,dword ptr [eax]
					assume eax:ptr WORDINFO
					.while eax!=0
						.if edx==[eax].WordLen</b></font></pre>
<p><font face="Tahoma"><font size="-1">If the value in the dword is non-zero, 
  it points to the linked list of <font color="#006666"><b>WORDINFO</b></font> 
  structures. We process to walk the linked list, comparing the length of the 
  word in our local buffer with the length of the word in the <font color="#006666"><b>WORDINFO</b></font> 
  structure. This is a quick test before we compare the words. Should save some 
  clock cycles.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>							pushad
							invoke lstrcmpi,[eax].pszWord,esi
							.if eax==0</b></font></pre>
<p><font face="Tahoma"><font size="-1">If the lengths of both words are equal, 
  we proceed to compare them with <font color="#006666"><b>lstrcmpi</b></font>.</font><b> 
  </b></font></p>
<pre><font face="Tahoma"><b>								popad
								mov ecx,esi
								lea edx,buffer
								sub ecx,edx
								add ecx,FirstChar</b></font></pre>
<p><font face="Tahoma"><font size="-1">We construct the character index from the 
  address of the first character of the matching word in the buffer. We first 
  obtain its relative offset from the starting address of the buffer then add 
  the character index of the first visible character to it.</font><b> </b></font></p>
<pre><font face="Tahoma"><b>								pushad
								.if RichEditVersion==3
									invoke SendMessage,hWnd,EM_POSFROMCHAR,addr rect,ecx
								.else
									invoke SendMessage,hWnd,EM_POSFROMCHAR,ecx,0
									mov ecx,eax
									and ecx,0FFFFh
									mov rect.left,ecx
									shr eax,16
									mov rect.top,eax
								.endif
								popad</b></font></pre>
<p><font face="Tahoma"><font size="-1">Once we know the character index of the 
  first character of the word to be hilighted, we proceed to obtain the coordinate 
  of it by sending <font color="#006666"><b>EM_POSFROMCHAR</b></font> message. 
  However, this message is interpreted differently by richedit 2.0 and 3.0. For 
  richedit 2.0, <font color="#0000CC"><b>wParam</b></font> contains the character 
  index and <font color="#0000CC"><b>lParam</b></font> is not used. It returns 
  the coordinate in eax. For richedit 3.0, <font color="#0000CC"><b>wParam</b></font> 
  is the pointer to a <font color="#006666"><b>POINT</b></font> structure that 
  will be filled with the coordinate and <font color="#0000CC"><b>lParam</b></font> 
  contains the character index. </font></font></p>
<p><font face="Tahoma"><font size="-1">As you can see, passing the wrong arguments 
  to <font color="#006666"><b>EM_POSFROMCHAR</b></font> can wreak havoc to your 
  system. That's why I have to differentiate between RichEdit control versions.</font><b> 
  </b></font></p>
<pre><font face="Tahoma"><b>								mov edx,[eax].pColor
								invoke SetTextColor,hdc,dword ptr [edx]								
								invoke DrawText,hdc,esi,-1,addr rect,0</b></font></pre>
<p><font face="Tahoma" size="-1">Once we got the coordinate to start, we set the 
  text color with the one specified in the <font color="#006666"><b>WORDINFO</b></font> 
  structure. And then proceed to overwrite the word with the new color.</font></p>
<p><font face="Tahoma" size="-1">As the final words, this method can be improved 
  in several ways. For example, I obtain all the text starting from the first 
  to the last visible line. If the lines are very long, the performance may hurt 
  by processing the words that are not visible. You can optimize this by obtaining 
  the really visible text line by line. Also the searching algorithm can be improved 
  by using a more efficient method. Don't take me wrong: the syntax hilighting 
  method used in this example is FAST but it can be FASTER. :)</font></p>
<hr>
<p align="center"><font face="Tahoma" size="-1"><b>[<a href="http://win32asm.cjb.net">Iczelion's 
  Win32 Assembly Homepage</a>]</b></font></p>
<p>&nbsp;</p>
<p><font face="Tahoma"><b><br>
  </b></font></p>
<pre>&nbsp;</pre>
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