What does this code do? .model small .386 .stack 100h .data msg1 db 13, 10, "Enter any number --> ", "$" msg2 db "Enter an operation +,- * or / --> ",13, 10, "$" msg3 db "The Operation is --> ", "$" msg4 db "The result is --> ", "$" By_base dd 21 by_10 dd 10 ; 32 bits variable with initial value = 10 sp_counter db 0 ; 8 bits variable with initial value of zero disp_number dd 0 ; 32 bits variable with initial value = 0 disp_number2 dd 0 disp_number3 dd 0 op_type db 0 last_key dd 0 ; 32 bits variable with initial value of zero remainder db 0 .code main proc mov ax,@data ; set up data segment mov ds,ax mov dx,offset msg1 call display_message call m_keyin
What does this code do?
.model small
.386
.stack 100h
.data
msg1 db 13, 10, "Enter any number --> ", "$"
msg2 db "Enter an operation +,- * or / --> ",13, 10, "$"
msg3 db "The Operation is --> ", "$"
msg4 db "The result is --> ", "$"
By_base dd 21
by_10 dd 10 ; 32 bits variable with initial value = 10
sp_counter db 0 ; 8 bits variable with initial value of zero
disp_number dd 0 ; 32 bits variable with initial value = 0
disp_number2 dd 0
disp_number3 dd 0
op_type db 0
last_key dd 0 ; 32 bits variable with initial value of zero
remainder db 0
.code
main proc
mov ax,@data ; set up data segment
mov ds,ax
mov dx,offset msg1
call display_message
call m_keyin
call operation
mov dx,offset msg1
call display_message
call m_keyin
cmp op_type, "+"
jnz short skip_plus
call op_plus
skiP_plus:
cmp op_type, "-"
jnz short skip_minus
call op_minus
skip_minus:
cmp op_type, "*"
jnz short skip_mul
call op_mult
skip_mul:
cmp op_type, "/"
jnz short skip_div
call op_div
skip_div:
call m_display
mov ax, 4c00h
int 21h
operation proc
mov dx,offset msg2
rpt4:
call display_message
mov dx,offset msg3
call display_message
mov ah, 1
int 21h
cmp al, 30h
jns rpt4
mov op_type, al
ret
operation endp
m_display proc
mov dx,offset msg4
call display_message
mov eax, disp_number
mov sp_counter, 0
Base_lp:
LP1:
mov edx, 0
div By_Base
push dx
inc sp_counter
cmp eax, 0
jnz lp1
LP2:
pop dx
call display
dec sp_counter
jnz lp2
mov edx, -8
call display
mov edx, by_base
call display
mov edx, -7
call display
dec By_base
mov eax, disp_number
cmp By_base, 1
jnz Base_lp
ret
m_display endp
op_minus proc
mov eax, disp_number2
sub eax, disp_number3
mov disp_number, eax
ret
op_minus endp
op_div proc
mov eax, disp_number2
div disp_number3
mov disp_number, eax
mov remainder, dl
call display
call m_display
mov dl, -16
call display
mov dl, remainder
call display
mov dl, -1
call display
mov edx, disp_number3
call display
mov ax, 4c00h
int 21h
op_div endp
op_mult proc
mov eax, disp_number2
mul disp_number3
mov disp_number, eax
ret
op_mult endp
op_plus proc
mov eax, disp_number2
add eax, disp_number3
mov disp_number, eax
ret
op_plus endp
display proc
add dl, 30h
cmp dl, 3ah
js short skip_hex
add dl, 7
Skip_hex:
mov ah, 6
int 21h
ret
display endp
display_message proc
mov ah, 9 ; to display to screen the string pointed by the DX register.
int 21h
mov edx, 0
ret
display_message endp
m_keyin proc
MOV disp_number, 0
mov last_key, 0
LP_key:; location in the program label
mov eax, disp_number
mul by_10 ; eax = (eax) * 10
add eax, last_key
mov DISP_NUMBER, eax ; save it to the number to display
mov ah, 1 ; enables a single key entry
int 21h
AND eax, 000000ffh
cmp al, 13 ; compare the key entered to 13 i.e. ascii of CR
jz short finkey ; if CR was pressed then exit the enter key routine
sub al, 30h ; remove the ascii from the number entered to get a pure number.
MOV LAST_KEY, EAX ; save the last digit entered
jmp lp_key ; unconditional jump to the enter key routine in a loop
finkey:
MOV eax, DISP_NUMBER
cmp DISP_NUMBER2,0
jnz short skip
MOV DISP_NUMBER2, EAX
skip:
MOV DISP_NUMBER3, EAX
ret
m_keyin endp
main endp
end main
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