Hello,
I just need an instr-function like I know in Basic and other high-level programming languages. I tried to build it on my own, but it seems I'm not able to find the error - the procedure returns 0, anyway.
Perhaps, anyone will be able to find my error, it would be really great :) .
My concept is to find the first match of the first character of the substring at first. If I have found one, I just check wheter the following characters match, too, otherwise go on searching the next match of the first character.
Thanks to everybody who just reads this message or even tries to help me, and I'd love to have some nice answers ( ;) )
yours,
Claus
I just need an instr-function like I know in Basic and other high-level programming languages. I tried to build it on my own, but it seems I'm not able to find the error - the procedure returns 0, anyway.
Perhaps, anyone will be able to find my error, it would be really great :) .
My concept is to find the first match of the first character of the substring at first. If I have found one, I just check wheter the following characters match, too, otherwise go on searching the next match of the first character.
InstrEx PROC StartPos:DWORD, String:DWORD, SubString:DWORD
mov eax, String
dec eax
dec eax
add eax, StartPos
;find first match of the first char
FindFirst:
inc eax
mov ebx, [eax]
mov ecx, SubString
mov ecx, [ecx]
cmp ebx, ecx
je FoundFirst
cmp ebx, 0
je NotFound
jmp FindFirst
FoundFirst: push eax
mov ecx, SubString
dec ecx
push ecx
CompareLoop: pop ecx
inc ecx
mov ebx, [eax]
push ecx
mov ecx, [ecx]
cmp ecx, 0
je Found
cmp ecx, ebx
je CompareLoop
FalseFirst:
pop eax
jmp FindFirst
Found: pop eax
sub eax, String
jmp Done
NotFound: mov eax, 0
Done: ret
InstrEx ENDPThanks to everybody who just reads this message or even tries to help me, and I'd love to have some nice answers ( ;) )
yours,
Claus
Oh,
well, the code doesn't look very well, it seems I used sometimes tabs, sometimes just spaces. In my editor, it looks really fine ...
well, the code doesn't look very well, it seems I used sometimes tabs, sometimes just spaces. In my editor, it looks really fine ...
MASM32 package has a MASM32.lib with a InString procedure with source. For some working code you can look at.
Regards, P1 :cool:
Regards, P1 :cool:
would still be nice to fix the source problem though - people will learn from that. I'm too tired to have a look at the source right now though :)
This *seems* to work, from your original algo with some changes, you were not popping ecx in case of a not found and messing up the stack, as well as fixing up a few logic problems. I haven't thoroughly tested it but it should be pretty close to OK.
InstrEx FRAME StartPos, String, SubString
mov eax, [String]
dec eax
add eax, [StartPos]
mov ecx, [SubString]
;find first match of the first char
FindFirst: inc eax
mov bl, [eax]
mov dl, [ecx]
cmp bl, dl
je >FoundFirst
cmp bl, 0
je >NotFound
jmp FindFirst
FoundFirst: push eax
dec ecx
dec eax
CompareLoop: inc ecx
inc eax
mov bl, [eax]
mov dl, [ecx]
cmp dl, 0
je >Found
cmp dl, bl
je CompareLoop
FalseFirst: pop eax
mov ecx, [SubString]
jmp FindFirst
Found: pop eax
sub eax, [String]
jmp >Done
NotFound: mov eax, 0
Done: ret
ENDFHello,
thanks for your help, especially to donkey, it is really fine for a beginner like me.
I will have a look at the InString-Function in the Masm32-Library, but I'd like to finish my own version, just for learning.
The code of donkey seems to be problematic:
First, I didn't know a FRAME yet, and I didn't get it working. Is it like a PROC or like a MACRO? How can I use it?
So, I couldn't test the source, but I have some questions nevertheless:
1) mov eax, (line 3) : Why do you use [] ? I think I have to use the memory address, so that I can increment or decrement it. By now, I think the first character is incremented or decremented! The same with line 5 and 6.
2) Why do you always put a > after jumping-instructions? My Masm32 says this is an error?
Of course, my greatest problem was that I just compared 4 bytes each time instead of only one byte.
I hope you can answer my (perhaps stupid) questions. And thank you another time for the replies.
Regards,
Claus
thanks for your help, especially to donkey, it is really fine for a beginner like me.
I will have a look at the InString-Function in the Masm32-Library, but I'd like to finish my own version, just for learning.
The code of donkey seems to be problematic:
First, I didn't know a FRAME yet, and I didn't get it working. Is it like a PROC or like a MACRO? How can I use it?
So, I couldn't test the source, but I have some questions nevertheless:
1) mov eax, (line 3) : Why do you use [] ? I think I have to use the memory address, so that I can increment or decrement it. By now, I think the first character is incremented or decremented! The same with line 5 and 6.
2) Why do you always put a > after jumping-instructions? My Masm32 says this is an error?
Of course, my greatest problem was that I just compared 4 bytes each time instead of only one byte.
I hope you can answer my (perhaps stupid) questions. And thank you another time for the replies.
Regards,
Claus
Well donkey uses goasm and not masm, so his code will look un-masmish. FRAME is like proc in masm if I am not wrong. I leave it for donkey to explain the rest.
Hello,
OK, but with donkey's help, I was able to get my version running:
Now, I will have to test the performance of my code and the masm32-included code, but I think I won't have a chance.
Regards,
Claus
OK, but with donkey's help, I was able to get my version running:
InstrEx PROC StartPos:DWORD, String:DWORD, SubString:DWORD
mov eax, String
dec eax
dec eax
add eax, StartPos
;find first match of the first char
FindFirst:
inc eax
mov dl, [eax]
mov ecx, SubString
mov dh, [ecx]
cmp dl, dh
je FoundFirst
cmp dl, 0
je NotFound
jmp FindFirst
FoundFirst:
push eax
mov ecx, SubString
dec ecx
dec eax
CompareLoop: inc ecx
inc eax
mov dl, [eax]
mov dh, [ecx]
cmp dh, 0
je Found
cmp dh, dl
je CompareLoop
FalseFirst:
pop eax
jmp FindFirst
Found: pop eax
sub eax, String
jmp Done
NotFound: mov eax, 0
Done: ret
InstrEx ENDP
Now, I will have to test the performance of my code and the masm32-included code, but I think I won't have a chance.
Regards,
Claus
Claus von der Burchard,
The other 2 questions you posted are also GoAsm syntax related. The [] is "Proper Intel" syntax, (correct me if I'm wrong), I think NASM also uses it, MASM discards these for 'ease of use'. And the < > lines in the jumps are like MASM @B and @F.
Regards
The other 2 questions you posted are also GoAsm syntax related. The [] is "Proper Intel" syntax, (correct me if I'm wrong), I think NASM also uses it, MASM discards these for 'ease of use'. And the < > lines in the jumps are like MASM @B and @F.
Regards
Claus,
Scanner style string searches all have more or less the same logic unless you want to try out some of the exotic ones. You scan the source for the first character in the string you are trying to find, when you find it you branch to a comparison routine to see if the rest of the string matches. If it does you return the offset of the start character and if it does not, you go back to scanning the source.
You will find the one in MASM32 works OK but it is a good idea to write your own as it tunes you to writing your own algorithms and you can make dedicated algos then if you need them.
Regards,
hutch at movsd dot com
Scanner style string searches all have more or less the same logic unless you want to try out some of the exotic ones. You scan the source for the first character in the string you are trying to find, when you find it you branch to a comparison routine to see if the rest of the string matches. If it does you return the offset of the start character and if it does not, you go back to scanning the source.
You will find the one in MASM32 works OK but it is a good idea to write your own as it tunes you to writing your own algorithms and you can make dedicated algos then if you need them.
Regards,
hutch at movsd dot com
Hi Claus,
I am very sorry I did not respond earlier, I missed this thread in the RSS feed. As others have said, I use GoAsm and tend to post in that syntax as I am better set up to test with it. Everybody appears to have answered your syntax questions, GoAsm is very close in syntax to MASM except for the jmp > < stuff and FRAME/ENDF instead of PROC/ENDP. There are a few other differences but they are minor, mostly scoping of labels, GoAsm has much more powerful scoping than MASM. In the code posted you can just leave out the > or < completely and change the FRAME/ENDF.
I am very sorry I did not respond earlier, I missed this thread in the RSS feed. As others have said, I use GoAsm and tend to post in that syntax as I am better set up to test with it. Everybody appears to have answered your syntax questions, GoAsm is very close in syntax to MASM except for the jmp > < stuff and FRAME/ENDF instead of PROC/ENDP. There are a few other differences but they are minor, mostly scoping of labels, GoAsm has much more powerful scoping than MASM. In the code posted you can just leave out the > or < completely and change the FRAME/ENDF.
Hi donkey,
Okay, I think every question is answered, by now.
Thanks, again.
Okay, I think every question is answered, by now.
Thanks, again.
OK,
just a new problem with Instr:
I want to search a string which has nullchars inside. I know the length of the string, so it shouldn't be a problem. Of course, there is one, as my program chrashes less than a second after terminating the Instr-Proc, although the Instr-function replied the right value.
Is there any problem with this function:
Regards,
Claus
just a new problem with Instr:
I want to search a string which has nullchars inside. I know the length of the string, so it shouldn't be a problem. Of course, there is one, as my program chrashes less than a second after terminating the Instr-Proc, although the Instr-function replied the right value.
Is there any problem with this function:
InstrEx PROC StartPos:DWORD, String:DWORD, SubString:DWORD, StrLength:DWORD
mov eax, StrLength
add eax, String
mov StrLength, eax
mov eax, String
dec eax
dec eax
add eax, StartPos
;find first match of the first char
FindFirst:
inc eax
cmp StrLength, eax
je NotFound
mov dl, [eax]
mov ecx, SubString
mov dh, [ecx]
cmp dl, dh
je FoundFirst
cmp eax, ebx
je NotFound
jmp FindFirst
FoundFirst:
push eax
mov ecx, SubString
dec ecx
dec eax
CompareLoop: inc ecx
inc eax
cmp StrLength, eax
je FalseFirst
mov dl, [eax]
mov dh, [ecx]
cmp dh, 0
je Found
cmp dh, dl
je CompareLoop
FalseFirst:
pop eax
jmp FindFirst
Found: pop eax
sub eax, String
jmp Done
NotFound: mov eax, 0
Done: ret
InstrEx ENDP
Regards,
Claus