; @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@
(Function: Demonstration to determine if a string is a function of a substring of another string
; Author: Huang Zhibin in Hechi
Daily period
; ------------------------------------------------- ---
2002.06.25 Complete basic functions
2002.06.26 Modify Issubstr to reduce one byte
2002.06.29 Discover the algorithm error used in the 26th to modify, modify the calculation string 1
; Algorithm in the skewer 2, the file length is reduced to 320 bytes
Codeseg segment
; ================================================== ===
ORG 100H
Assume ES: Codeseg, SS: CODESEG, CS: CODESEG, DS: CODESEG
; -----------------------------
Main Proc
MOV DX, Offset StrPt
MOV AH, 9
Int 21h
MOV DX, Offset str1maxlen
Mov Ah, 0ah
Int 21h
Call CRLINE
MOV CSTRNAME, '2'
MOV DX, Offset StrPt
MOV AH, 9
Int 21h
Mov DX, Offset Str2maxlen
Mov Ah, 0ah
Int 21h
Call CRLINE
XOR CH, CH
MOV CL, STR1LEN
XOR BH, BH
MOV BL, STR2LEN
Mov Si, Offset String1
Mov Di, Offset String2
Call Issubstr
MOV DX, Offset Strisnull
CMP BP, -3
Je @quit
MOV DX, Offset Strtoolen
CMP BP, -2
Je @quit
MOV DX, Offset Strno
CMP BP, -1
Je @quit
Mov Di, Offset CPSITION
MOV AX, BP
Call Dec2ASCII
MOV DX, Offset Stryes
@Quit:
MOV AH, 9
Int 21h
MOV AX, 4C00H
Int 21h
Main endp
; ----------------------
Conststrlen EQU 15
STRPROMPT DB "Enter"
CSTRNAME DB '1'
DB "string: $"
STR1MAXLEN DB Conststrlenstr1len DB 0
String1 DB Conststrlen Dup (?)
STR2MAXLEN DB Conststrlen
Str2len DB 0
String2 DB Conststrlen Dup (?)
STRTOOLEN DB "String 1 is greater than the string 2! $"
Strisnull DB "String 1 length is 0 $"
Stryes DB "String 1 appears in string 2 left"
CPSITION DB "Location $"
Strno DB 0DH, 0AH, "String 1 is not string of string 2 $"
; ============================================
; Function: Convert data in AX into a corresponding decimal number string
;enter:
; AX = data to be converted
; Di = buffer first address of the string of the converted string
; Output: None
; --------------------------------------------
Dec2ascii proc
MOV CX, 2
MOV DL, 100
@Loopdiv:
Div DL
Add Al, '0'
MOV [DI], Al
INC DI
Mov Al, AH
XOR AH, AH
SHR DL, 1
Loop @loopdiv
Add Al, '0'
MOV [DI], Al
RET
DEC2ASCII ENDP
; ===================================
; Function: Judging whether the string 1 is a string of string 2
;Entrance:
; Cx = length of string 1
; Bx = length of string 2
; Si = start address of string 1
; Di = start address of string 2
;Exit:
BP> = 0 string 1 is a string of string 2, and BP = string 1 in series 2 in series (starting from 0)
BP = -1 string 1 is not a string of string 2
; BP = -2 string 1 length is greater than string 2
; BP = -3 string 1 length is 0
; ----------------------------------
Issubstr Proc
PUSH DI; Save String 2 Addition Location
MOV BP, -3
JCXZ @ERRRRESULT
MOV BP, -2
CMP CX, BX
Jg @errresult
CLD
@Loopcmp:
PUSH CX
Push Si
Push di
REPE CMPSB
Je @YESRESULT
POP DI; Restore String 2 Preferred in this comparison
INC DI; add 1 to 1, point to the next character so that the next time
Dec BX; string 2 length minus 1
POP Si; Restore String 1 Address
POP CX; restore string 1 length
CMP BX, CX
JGE @loopcmp
MOV BP, -1 @ errRRRRESULT:
POP CX
RET
@YESRESRESRESRESULT:
The following is a method of initially calculating the position of string 1 in series 2
Pop AX; these 2 are Di, Si that pops up previously pressed
; POP AX
; POP CX; send the string 1 length to CX
; POP BP; send the original string 2 to the first spot
; SUB DI, CX; Calculate the first address of this comparison time
SUB DI, BP; String 1 in series 2 = Preferred in this comparison - the first address of the original string 2
; MOV BP, DI
RET
POP BP; popped up previously pressed DI, that is, the first address of the string 2 at this time
POP AX; pops up Si, useless
POP CX; send CX 1 length
POP DI; send the original string 2 to send DI
SUB BP, DI; Calculation String 1 in the string 2
RET
Issubstr ENDP
; ======================
CRLINE PROC
MOV DX, Offset strcrline
MOV AH, 9
Int 21h
RET
CRLINE ENDP
; ----------------------
Strcrline DB 0DH, 0AH, '$'
Codeseg Ends
End main
Error algorithm:
Since there is no address of the string 2, it is "123", the string 2 is "12345" when the string 1 is "12345".
The result of the operation is "String 1 is not a string of string 2"
Issubstr Proc
PUSH DI; Save String 2 length After calculation string 1 appearance position
MOV BP, -3
JCXZ @ERRRRESULT
MOV BP, -2
CMP CX, BX
Jg @errresult
CLD
@Loopcmp:
PUSH CX
Push Si
REPE CMPSB
JE @YesResult; is a substring to jump
POP Si
The following three instructions are the latest residual length of the string 2
The number of bytes compared to the system = string 1 length - CX
; bx = string 2 original remaining length
; String 2 latest remaining length = string 2 original remaining length - the number of bytes that have been compared
; = BX - (String 1 length - CX)
; = BX CX - String 1 length
Add BX, CX; Performance BX = String 2 Length
POP CX; Restore String 1 Address
SUB BX, CX; CX = String 1 length, after execution BX = string 2 latest remainder
CMP BX, CX
JGE @loopcmp
MOV BP, -1
@ERRRESULT:
POP CX
RET
@YESRESRESRESRESULT:
POP AX; this is Si that pops up the previously pressed
POP CX; send CX 1 length
POP BP; Send BP 2 length
SUB DI, CX; The following three instructions calculation string 1 in series 2 is stored in BP
SUB DI, BP
MOV BP, DI
RET
Issubstr ENDP
; ==================================================== Codeseg Ends
End main
