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> Windows > Compare String |
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Madis731 19 Nov 2004, 10:16
Why haven't you done your homework :@
CMPSB Compare Strings Code: CMPSB ; A6 [8086] CMPSW ; o16 A7 [8086] CMPSD ; o32 A7 [386] CMPSB compares the byte at [DS:SI] or [DS:ESI] with the byte at [ES:DI] or [ES:EDI], and sets the flags accordingly. It then increments or decrements (depending on the direction flag: increments if the flag is clear, decrements if it is set) SI and DI (or ESI and EDI). The registers used are SI and DI if the address size is 16 bits, and ESI and EDI if it is 32 bits. If you need to use an address size not equal to the current BITS setting, you can use an explicit a16 or a32 prefix. The segment register used to load from [SI] or [ESI] can be overridden by using a segment register name as a prefix (for example, ES CMPSB). The use of ES for the load from [DI] or [EDI] cannot be overridden. CMPSW and CMPSD work in the same way, but they compare a word or a doubleword instead of a byte, and increment or decrement the addressing registers by 2 or 4 instead of 1. The REPE and REPNE prefixes (equivalently, REPZ and REPNZ) may be used to repeat the instruction up to CX (or ECX - again, the address size chooses which) times until the first unequal or equal byte is found. Winamp control I understand - but over TELNET? What do you mean? Think you meant TCP/IP -OR- are you using only a specific port? Anyway, you would have to run one instance of winamp on your computer continuously and make a server to receive IP connections and parse them. Secondly you'd have to make a client on the other side while the server remains on a static IP so your client can send requests. I got to say, this is one hard thing to start with. But I admire what you are doing - you should post your progress on this forum. Cheers |
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19 Nov 2004, 10:16 |
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DEMON 19 Nov 2004, 18:46
WinApi function
Code: int lstrcmp( LPCTSTR lpString1, // address of first string LPCTSTR lpString2 // address of second string ); |
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19 Nov 2004, 18:46 |
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DEMON 19 Nov 2004, 18:47
WinApi function
Code: int lstrcmp( LPCTSTR lpString1, // address of first string LPCTSTR lpString2 // address of second string ); |
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19 Nov 2004, 18:47 |
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Vortex 19 Nov 2004, 20:16
Coded by Hutch:
Code: proc strcmp,str1,str2 mov ecx, str1 mov edx, str2 cmst: mov al, [ecx] cmp al, [edx] jne no_match add ecx, 1 add edx, 1 test al, al jne cmst xor eax,eax ret no_match: mov eax,1 return endp _________________ Code it... That's all... |
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19 Nov 2004, 20:16 |
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Matrix 19 Nov 2004, 20:28
Code: macro dos_writestr ._string121 {mov dx,._string121 call dosprint} org 256 push es push ds pop es mov esi,str3 ; source string mov edi,str4 ; destination string mov ecx,255 ; max lenght call compare_strings_and_write mov esi,str1 ; source string mov edi,str2 ; destination string mov ecx,255 ; max lenght call compare_strings_and_write mov esi,str3 ; source string mov edi,str4 ; destination string mov ecx,255 ; max lenght call compare_strings_and_write pop es xor ah,ah int 16h int 20h compare_strings_and_write: pushf dos_writestr si dos_writestr di call cmpstr0 jne .not_equal_label dos_writestr _equal jmp .equal_label .not_equal_label: dos_writestr _not_equal .equal_label: popf ret dosprint: mov ah,9 int 21h ret str1: db 'i am string 1',13,10,'$',0 str2: db 'i am string 1',13,10,'$',0 str3: db 'i am string 3',13,10,'$',0 str4: db 'i am string 4',13,10,'$',0 _equal: db 'EQUAL',13,10,'$' _not_equal: db 'NOT EQUAL',13,10,'$' cmpstr0: ;compare string ds:(e)si with es:(e)di, (e)cx=max lenght, returns zero if equal (e) mov edx,edi ; save source pointer repnz scasb ; get string 1 end mov ecx,edi sub ecx,edx mov edi,edx repe cmpsb ; compare strings or ecx,ecx ;jecxz ._equal ; if not equal then bytes left ;clc ;jmp ._not_equal ;._equal: ; equal ;stc ;._not_equal: ret i was thinking something like this, Last edited by Matrix on 20 Nov 2004, 08:56; edited 6 times in total |
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19 Nov 2004, 20:28 |
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Madis731 19 Nov 2004, 22:06
Isn't there a bug?
Your code always shows you NOT equal because even if unequal byte is found, you test it against 0 but it doesn't have to be the case: str1 db "string",0,46,86,129,... str2 db "string",0,13,35,... repe exits when 46<->13 are compared Two digits can NEVER be zero when, the are different I can't fix your code - it becomes so complicated. I'd rather suggest my own strcmp routine (DWORD is faster with longer strings): Code:
mov esi,str1
mov edi,str2
cld ;use it (unless you are REALLY sure)
jmp .cut_in
.the_loop:
add esi,4
add edi,4
.cut_in:
mov eax,[esi]
mov edx,[edi]
cmp eax,edx
je .the_loop
.final_tests:
cmpsb
jne .dif
cmp [esi],byte 0
je .equ
jmp .final_tests
.dif: ;No, they don't match!
.equ: ;Yes, equal they are!
str1 db "Tere, mina olen üks string",0
str2 db "Tere, mina olen üks strin",0
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19 Nov 2004, 22:06 |
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Matrix 20 Nov 2004, 07:26
doesn't have to be the case:
str1 db "string",0,46,86,129,... str2 db "string",0,13,35,... repe exits when 46<->13 are compared two string cannot be equal if the zero terminators are not @the same place, why are you putting 0 @the middle of the 0 terminated string? my code not working? sorry, its fixed |
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20 Nov 2004, 07:26 |
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Matrix 20 Nov 2004, 08:43
how come compare string is not in main?
Scientica? what do you think? |
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20 Nov 2004, 08:43 |
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Madis731 20 Nov 2004, 14:52
Yes, it should have its own place in main.
Matrix: Your code seems to work without errors this time, great code! |
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20 Nov 2004, 14:52 |
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Matrix 21 Nov 2004, 03:47
Thnx Madis731
btw.: my compare code won't be too slow compared to a single loop one, (cause the source string is mapped into cache during first loop if string is less then about 8 KB) i'll post the next version, but for small ~100 byte strings it counts nearly nothing. |
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21 Nov 2004, 03:47 |
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Matrix 21 Nov 2004, 08:28
here you are, maeby a bit faster
ready for testing Code: macro dos_writestr ._string121 {mov dx,._string121 call dosprint} org 256 push es push ds pop es mov esi,str3 ; source string mov edi,str4 ; destination string ;mov ecx,255 ; max lenght call compare_strings_and_write mov esi,str1 ; source string mov edi,str2 ; destination string ;mov ecx,255 ; max lenght call compare_strings_and_write mov esi,str3 ; source string mov edi,str4 ; destination string ;mov ecx,255 ; max lenght call compare_strings_and_write pop es xor ah,ah int 16h int 20h compare_strings_and_write: dos_writestr si dos_writestr di call cmpstr0 jne .not_equal_label dos_writestr _equal jmp .equal_label .not_equal_label: dos_writestr _not_equal .equal_label: ret dosprint: mov ah,9 int 21h ret str1: db 'i am string 1',13,10,'$',0 str2: db 'i am string 1',13,10,'$',0 str3: db 'i am string 3',13,10,'$',0 str4: db 'i am string 4',13,10,'$',0 _equal: db 'EQUAL',13,10,'$' _not_equal: db 'NOT EQUAL',13,10,'$' cmpstr0b: ;compare string ds:(e)si with es:(e)di, (e)cx=max lenght, returns zero if equal (e) mov edx,edi ; save source pointer repnz scasb ; get string 1 end mov ecx,edi sub ecx,edx mov edi,edx repe cmpsb ; compare strings or ecx,ecx ret cmpstr0: ;compare string ds:(e)si with es:(e)di, returns zero if equal (e) lodsb inc di or al,al jz .zero cmp [es:di-1],al je cmpstr0 .zero: cmp byte [es:di-1],0 ret |
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21 Nov 2004, 08:28 |
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