/ / Comparison test 1: two equal strings / Load NameAddr / Store CmpStringAddr1
ID: 3742147 • Letter: #
Question
/ / Comparison test 1: two equal strings
/ Load NameAddr
/ Store CmpStringAddr1
/ Load NameAddr
/ Store CmpStringAddr2
/ JnS CmpString
/ Load CmpStringResult
/ Output
CmpStringAddr1, HEX 0 / address of first string to compare
CmpStringAddr2, HEX 0 / address of second string to compare
CmpStringResult, DEC 0 / the result of the comparison (-1: less, 0: equal, 1: greater)
CmpString, HEX 0 / the label of the subroutine
/ <--- this is where you add your code for comparison
/ <--- this is where you add more comparison test cases
2.4 String comparison (15 points) Now we are going to implement a string comparison subroutine. We will use lexicoaraphic ordering, i.e., the ordering you would use e.g. when sorting names alphabetically. The subroutine takes two (addresses of) strings as arguments and returns -1 if the first string is lexicographically smaller than the second, 0 if they are equal, and 1 if the first string is lexicographically greater than the second string. For example, ABCD is smaller than BCDEF (because the first character is smaller), ABC is smaller than ABCDE (because it is a proper prefix), and BCDF is greater than BCDE (because the first character that is different, the F, is greater The subroutine will communicate the result back to the caller (the code that called JnS in the address with the label CmpStringResult, i.e., after returning from the subroutine. CmpStringResult will be equal to -1 if the first string is smaller, 0 if the strings are equal and 1 if the first string is greater.Explanation / Answer
Data_segment_name segment para RetAddress dw ? NAME_TABLE db 10 dup(11,0,12 dup('$')) L1 db '143','$','$','$','$','$','$','$' L2 db '143435879','$','$' L3 db '143452879','$','$' CMPStringResult db ? MinStringAddr dw ? AXT dw ? BXT dw ? CXT dw ? DXT dw ? BPT dw ? SIT dw ? DIT dw ? Data_segment_name ends ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Stack_segment_name segment para stack db 32h dup(0FFh) ;define your stack segment Stack_segment_name ends ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Code_segment_name segment Main_prog proc far assume SS:Stack_segment_name,CS:Code_segment_name,DS:Data_segment_name MOV AX,Data_segment_name MOV DS,AX CALL InputStrings CALL InsertionSort CALL PrintStrings CLOSE:MOV AH,4Ch ; Exit program INT 21h Main_prog endp SaveRegisters PROC MOV AXT,AX MOV BXT,BX MOV CXT,CX MOV DXT,DX MOV BPT,BP MOV SIT,SI MOV DIT,DI RET SaveRegisters ENDP LoadRegisters PROC MOV AX,AXT MOV BX,BXT MOV CX,CXT MOV DX,DXT MOV BP,BPT MOV SI,SIT MOV DI,DIT RET LoadRegisters ENDP InputStrings PROC ;Save All Registers CALL SaveRegisters ;Save Flags PUSHF ;Input the Strings MOV BX,0 OL: LEA DX,NAME_TABLE[BX] MOV AH,0Ah INT 21h MOV DL,10 MOV AH,02 INT 21h ADD BX,14 CMP BX,14*10 JNZ OL EXIT3: ;Return Flags POPF ;Load All Registers CALL LoadRegisters ;Return RET InputStrings ENDP PrintStrings PROC ;Save All Registers CALL SaveRegisters ;Save Flags PUSHF MOV DL,10 MOV AH,02h INT 21h MOV BX,0 OL3: LEA DX,NAME_TABLE[BX+2] MOV AH,09 INT 21h MOV DL,10 MOV AH,02 INT 21h ADD BX,14 CMP BX,14*10 JNZ OL3 EXIT5: ;Return Flags POPF ;Load All Registers CALL LoadRegisters ;Return RET PrintStrings ENDP CMPString PROC ;Save All Registers CALL SaveRegisters ;Get Return Address POP RetAddress MOV AX,RetAddress ;Get Param2 - String 2 Address POP DI ;Get Param1 - String 1 Address POP SI ;Save Flags PUSHF ;Compare Strings MOV DX,Data_segment_name MOV DS,DX MOV ES,DX MOV CX,10 REPE CMPSB JL S1LessS2 JG S1MoreS1 S1EqualS2: MOV CMPStringResult,0 JMP EXIT1 S1LessS2: MOV CMPStringResult,-1 JMP EXIT1 S1MoreS1: MOV CMPStringResult,1 EXIT1: ;Return Flags POPF ;Return the Return Address PUSH RetAddress ;Load All Registers CALL LoadRegisters ;Return RET CMPString ENDP SwapString PROC ;Save All Registers CALL SaveRegisters ;Get Return Address POP RetAddress MOV AX,RetAddress ;Get Param2 - String 2 Address POP DI ;Get Param1 - String 1 Address POP SI ;Save Flags PUSHF ;Swap MOV CX,10 LOOP1:MOV AL,[SI] MOV AH,[DI] MOV [SI],AH MOV [DI],AL INC SI INC DI LOOP LOOP1 EXIT2: ;Return Flags POPF ;Return the Return Address PUSH RetAddress ;Load All Registers CALL LoadRegisters ;Return RET SwapString ENDP InsertionSort PROC ;Save All Registers CALL SaveRegisters ;Save Flags PUSHF MOV BX,0 OL2: LEA DX,NAME_TABLE[BX+2] MOV MinStringAddr,DX MOV SI,BX ADD SI,14 IL: LEA AX,NAME_TABLE[SI+2] PUSH AX PUSH MinStringAddr CALL CMPString CMP CMPStringResult,0 JG NTH MOV MinStringAddr,AX NTH: ADD SI,14 CMP SI,14*10 JNZ IL Push MinStringAddr Push DX CALL SwapString ADD BX,14 CMP BX,14*9 JNZ OL2 EXIT4: ;Return Flags POPF ;Load All Registers CALL LoadRegisters ;Return RET InsertionSort ENDP Code_segment_name ends end Main_prog
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