db "Please enter up to 256 characters (press Enter Key to finish): ",0dh,0ah,'$'

Transcription

1 PA4 Sample Solution.model large.stack 100h.data msg1 db "This programs scans a string of up to 256 bytes and counts the repetitions of the number 4206 and sums them.",0dh,0ah,'$' msg2 db "Please enter up to 256 characters (press Enter Key to finish): ",0dh,0ah,'$' msg3 db "Number of substrings: $" msg4 db "Total: $" msg5 db "New string with INEL inserted before every 4206 that doesn't have INEL already before it: ",0dh, 0ah, '$' cr db 0dh, 0ah, '$' array db 256 dup (?) ;array for storing the input string newarray db 512 dup (?) ;array for storing the resulting stirng decimalcount db 2 dup (?) ;array for storing the decimal representation of count decimaltotal db 6 dup (?) ;array for storing the decimal representation of the total count dw 0 ;holds the count j dw 0 ;index for addressing newarray.code.startup mov ax, 0 ;add a new interrupt to the interrupt vector table mov es, ax mov al, 80h ;interrupt 80H mov bl, 4

2 mul bl mov bx, ax ;multiply by 4 for the address ;move the result to bx mov si, offset search ;copy the address of search procedure into interrupt vector 80h mov es:[bx], si ;copy the address to the first two bytes of the interrupt vector add bx, 2 mov ax, cs mov es:[bx], ax ;copy the code segment address to the last two bytes of the interrupt vector add bx, 2 ;add another interrupt to the interrupt vector table mov si, offset sum ;copy the address of sum procedure into interrupt vector 81h mov es:[bx], si 81h ;copy the address of the sum procedure to the first two bytes of the interrupt vector add bx, 2 mov ax, cs mov es:[bx], ax ;copy the code segment address into the last two bytes of the interrupt vector mov ;copy address of data to the data segment mov ds, ax call getinput ;calls procedure to get the user input mov bx, offset array ;loads bx with the address of array mov cx, di ;loads cx with the index of the last array element accessed int 80h ;call interrupt 80h to count the repetitions of "4206"

3 mov count, dx mov j, si mov cx, count int 81h ;move the value of dx (the count of "4206") into the variable count ;move the index of newarray into variable j ;move the count total into cx ;call interrupt 81h to sum the repetitions ;the result is stored in DX-AX call print ;call the print procedure mov ax, 4c00h ; exit to operating system..exit convert macro a, b ;macro procedure local SUB30, FIN1 cmp b, 1 ;if b is 1, a is a string je SUB30 ;if b equals 1 jump to SUB30 add a, 30h ;if b not equals 1 add 30h to a to convert from number to ASCII jmp FIN1 ;jump to Fin1 SUB30: sub a, 30h ;subtracts 30h from a to convert form ASCII to number FIN1: ;end of macro

4 endm getinput proc near lea dx, msg1 ;load dx with the address of message 1 mov ah, 9 ;display message 1 lea dx, cr ;carriage return and enter lea dx, msg2 ;load dx with address of message 2 ;display message 2 mov bx, offset array ;load bx with starting address of array mov di, 0 ;load di with 0 for indexing mov cx, 256 ;load the counter with 256 GET: mov ah, 1 ;get number from console cmp al, 0dh je enterkey ;compare with ascii value for Enter Key ;jump if equals to enterkey label and exit the loop

5 mov [bx+di], al ;if not equal, store the value into the array loop GET ;increment the index ;if cx is not zero, jump to GET enterkey: ;end of procedure ret getinput endp print proc near ;procedure for printing the numbers and final string of newarray push ax ;push dx-ax into the stack, these contain the final sum push dx lea dx, cr ;carriage return and newline mov ah, 9 lea dx, msg3 ;print message "Number of substrings: " mov bx, offset decimalcount ;load bx with the address of decimalcount array mov di, 0 mov ax, count ;load di with 0 for indexing ;copy the value of count into ax

6 mov cx, 0 ;load cx with 0 mov si, 0 ;load si with 0 for compare macro procedure C1: ;convert the count to decimal mov ah, 0 mov cl, 10 div cl ;divide the count by 10 convert ah, si mov [bx+di], ah ;send the remainder to convert procedure to convert to ASCII ;save the remainder in decimalcount[di] ;increment the index to address next element cmp al, 0 ;compare quotient with 0 ja C1 ;if above, jump to C1 and repeat P1: ;this part prints the remainders saved in decimalcount in reverse order dec di ;decrement the index for addressing the next element mov dl, [bx+di] ;load dl with the value of decimalcount[di] mov ah, 2 ;display value on screen cmp di, 0 ;compare the index with 0 ja P1 ;if above, jump to P1 and repeat lea dx, cr ;carriage return and newline mov ah, 9 lea dx, msg4 ;print message "Total: "

7 mov bx, offset decimaltotal ;load bx with the address of decimaltotal array pop dx ;get the total from the stack and store in DX-AX pop ax mov di, 0 ;clear di to 0 for indexing C2: ;this part converts the sum total into decimal values and stores them in decimatotal mov cx, 10 ;divide dx-ax by 10 div cx convert dl, si ;convert the remainder to ASCII value mov [bx+di], dl ;store the reaminder in decimaltotal[di] mov dx, 0 ;increment the index for addressing the next element ;clear dx for the next division cmp ax, 0 ;compare ax with 0 ja C2 ;if ax is still not 0, jump to C2 to repeat division P2: ;this part prints the total dec di ;decrement the index for addressing the next element mov dl, [bx+di] ;gets a value from decimaltotal array mov ah, 2 ;display the value on screen cmp di, 0 ;compare the index with 0 ja P2 ;if above 0, jump to P2 and repeat lea dx, cr ;carriage return and newline

8 mov ah, 9 lea dx, msg5 ;display string "New string with INEL inserted before... " ;This part prints the new string mov bx, offset newarray ;load bx with the address of newarray mov di, 0 mov cx, j ;clear di for indexing ;copy the size of newarray into cx (the amount of elements stored) STRING: mov ah, 2 mov dl, [bx+di] ;load dl with the value in newarray[di] ;display value on screen ;increment the index to address the next element loop STRING ;repeat until cx reaches 0 ret ;end of printing procedure print endp search proc far sums them. ;This interrupt procedure searches for the characters "4206", counts the number and ;It also adds the string "INEL" to every 4206 that doesn't have INEL (not-case sensitive) already before it.

9 mov ax, 0 ;loads ax with 0 mov dx, 0 ;loads the counter with 0 mov di, 0 ;loads the index of array with 0 mov si, 0 ;loads the index of newarray with 0 L1: ;starts the search cmp di, cx ;check if di equal the index of the last element stored in array je FIN ;if equal, jump to FIN mov al, [bx+di] ;load al with the element at array[di] cmp al, '4' je L2 ;compare with the ASCII value '4' ;if equals, jump to L2 mov newarray[si], al ;if not equal store value in newarray[si] cmp di, cx jb L1 jmp FIN ;increment array index ;increment newarray index ;check if di equals the index of the last element stored in array ;jump if below to L1 to check the next element ;if equal, jump to FIN L2: mov newarray[si], al ;move the ASCII value '4' to newarray[si] mov al, [bx+di] cmp al, '2' ;load al with the next element of array ;compare with the ASCII value '2' je L3 cmp al, '4' ;if equal,jump to L3 ;compare al with the ASCII value '4'

10 je L1 ;if equal, jump to L1 to check if correct order mov newarray[si], al ;if not equal store the value in newarray[si] cmp di, cx jb L1 jmp FIN ;check if di equals the index of the last element stored in array ;jump if below to the start at L1 ;if di equals cx jump to FIN L3: mov newarray[si], al ;move the value '2' to newarray[si] mov al, [bx+di] cmp al, '0' ;load al with the next element of array ;compare with the ASCII value '0' je L4 cmp al, '4' je L1 ;if equal, jump to L4 ;compare al with the ASCII value '4' ;if equal, jump to L1 to check if correct order mov newarray[si], al ;if not equal store the value in newarray[si] cmp di, cx jb L1 jmp FIN ;check if di equals the index of the last element stored in array ;jump if below to the start at L1 ;if equal, jump to FIN

11 L4: mov newarray[si], al ;move the ASCII value '0' to newarray[si] mov al, [bx+di] cmp al, '6' ;load al with the next element of array ;compare with the ASCII value '6' je CT cmp al, '4' je L1 ;if equal, jump to CT ;compare al with the ASCII value '4' ;if equal, jump to L1 to check if correct order mov newarray[si], al ;if not equal store the value in newarray[si] cmp di, cx jb L1 jmp FIN ;check if di equals the index of the last element stored in array ;if below, jump to start ;if equal jump to FIN CT: ;if it gets here a '4206' has been found mov newarray[si], al ;store the ASCII value of '6' in newarray[si] inc dx ;increment the counter push di ;store both indexes in the stack push si cmp di, 8 ;check if the array index is less than 8

12 jb ADJUST_DI ;if below, jump to ADJUST_DI sub di, 8 ;if not below, subtract 8 from both indexes to access 4 elements before the '4' sub si, 8 jmp INEL1 ;jump to INEL1 to check for the string "INEL" ADJUST_DI: ;This code loads the indexes with 0 to prohibit access to values outside the array mov di, 0 mov si, 0 INEL1: mov al, [bx+di] cmp al, 'I' je INEL2 cmp al, 'i' je INEL2 jne NOINEL ;checks for the character 'I' or 'i' ;loads al with the value four spaces before the value '4' ;compare the value stored in al with 'I' ;if equal, jump to INEL2 ;compare the value with 'i' ;if equal jump to INEL2 ;if not equal, jump to NOINEL INEL2: mov newarray[si], al ;store the value 'I' or 'i' in newarray[si] mov al, [bx+di] cmp al, 'N' je INEL3 cmp al, 'n' je INEL3 ;load al with the next value of array[di] ;compare the value stored in al with 'N' ;if equal, jump to INEL3 ;compare the value stored in al with 'n' ;if equal, jump to INEL3

13 jne NOINEL ;if not equal, jump to NOINEL INEL3: mov newarray[si], al ;store the value 'N' or 'n' in newarray[si] mov al, [bx+di] cmp al, 'E' je INEL4 cmp al, 'e' je INEL4 jne NOINEL ;load al with the next value of array[di] ;compare the value stored in al with 'E' ;if equal, jump to INEL4 ;compare the value with 'e' ;if equal, jump to INEL4 ;if not equal, jump to NOINEL INEL4: mov newarray[si], al ;store the value 'E' or 'l' in newarray[si] mov al, [bx+di] cmp al, 'L' je INELFOUND cmp al, 'l' je INELFOUND ;load al with the next value of array[di] ;compare the value stored in al with 'L' ;if equal, jump to INELFOUND ;compare the value stored in al with 'l' ;if equal, jump to INELFOUND NOINEL: pop si sub si, 4 ;If it gets here, no "INEL" was found before the "4206" so it is added to newarray[si] ;pop the original value from si (si points to the element after '6') ;subtract four to access element that has '4' mov newarray[si], 'I' ;copy "INEL4206" to newarray[si]

14 mov newarray[si], 'N' mov newarray[si], 'E' mov newarray[si], 'L' mov newarray[si], '4' mov newarray[si], '2' mov newarray[si], '0' mov newarray[si], '6' pop di jmp L1 ;pop the original value of di ;jump to the start at L1 INELFOUND: ;If it gets here an "INEL" has been found mov newarray[si], al ;store the value 'L' or 'l' fromt the las comparison in newarray[si] pop si ;pop the original values of the indexes pop di FIN: jmp L1 ;jump to the start at L1 ;end of interrupt procedure iret

15 search endp sum proc far ;this procedure sums "4206" the number of times it has been found mov ax, 4206 ;loads ax with 4206 mul cx iret ;multiplies ax by cx (cx contains the number of "4206" found in array) ;end of interrupt procedure sum endp end