assemblyx86masm

my assembly code doesnt run and i dont understand why

The assembly code initializes arrays A and B, calculates the element-wise sum of these arrays, and stores the results in array C. It also provides a procedure, printarray, to print the entire contents of an array and uses this procedure to print the values of arrays A, B, and C to the console. The code assumes a DOS-like environment and requires an x86-compatible system with appropriate assembly tools for execution. yet it didnt give me any result and when i tried debugging it exited the program

.model  small
.stack   100h
.data
A dw 12, 5, 8, -1, 4
B dw -2, 9, 0, 18, 3
C dw 5 dup (?)
N dw 5
.code
mov ax,@data
mov ds,ax
push offset A
push offset B
push offset C
push N
call arraysum
push offset A
push N
call printarray
mov ah, 2
mov dl, 10   
int 21h
push offset B
push N
call printarray
mov ah, 2
mov dl, 10   
int 21h
push offset C
push N
call printarray
mov ah, 2
mov dl, 10   
int 21h
.exit
sum proc near
push bp
mov bp,sp
mov ax,[bp+4]   
add ax,[bp+6]
pop bp
ret 4
sum endp
arraysum proc near
push bp
mov bp, sp
mov cx,[bp+4]
mov di, [bp + 10]
mov si, [bp + 8]
mov bx,[bp+6]
next:
push word ptr [di]
push word ptr [si]
call sum
pop word ptr [di]
pop word ptr [si]
mov [bx], ax
add si, 2  
add di, 2  
add bx, 2
dec cx
jnz next
pop bp
ret 8
arraysum endp

printnum proc near
    push bp
    mov bp, sp
    mov ax, [bp + 4] 
    mov bx, 10
    mov cx, 0
    
    cmp ax, 0 
    jge next
    neg ax
    
next1:   
    mov dx, 0
    div bx
    add dx, 30h
    push dx
    inc cx
    cmp ax, 0
    jne next1
    
    mov ax,[bp+4]
    cmp ax, 0
    jge sof
    push '-'
    inc cx
    
sof:
    cmp cx, 0
    jz ext
    pop dx
    mov ah, 2
    int 21h
    dec cx
    jmp sof
    
ext:
    pop bp
    ret 2   
printnum endp
printarray proc near
    push bp
    mov bp, sp
    mov cx, [bp + 4]  
    mov si, [bp + 6]  
    
print_loop:
    push word ptr [si]  
    call printnum       
    add sp, 2          
    inc si            
    dec cx            
    jnz print_loop     

    pop bp
    ret 4
printarray endp


end
Solution

  • I changed/added few things.

    1. OPTION NOKEYWORD:<C>, compiler no longer complains that this is keyword.
    2. Linespush offset A, B or C work when directives .186,.286,.286c or.286p are applied before .model. In other cases program compiles but doesn't print result on the screen or hangs. When .386 is after .model works as well. (https://stackoverflow.com/a/62603303/20889367)
    3. In sum proc, line ret 4 should be ret because after sum proc program pops values and ret 4 changed stack pointer to wrong location.
    4. Order of instructions after call to sum proc, should be pop word ptr [si], pop word ptr [di].
    5. printarray proc, value in cx is destroyed inside printnum proc so I added push cx / pop cx.
    6. In printnum proc I added 2 bytes to offset in lines mov ax, [bp + 6] because of the above cx instructions and procedure ends with ret not ret 2.
    7. Program ends correctly ax = 4c00h, int 21h.
    8. Code prints ' ' between values.

    Result:

    12 5 8 -1 4
-2 9 0 18 3
10 14 8 17 7

    Code:

    OPTION NOKEYWORD:<C>

.286
.model  small
.stack   100h

.data
    A dw 12, 5, 8, -1, 4        
    B dw -2, 9, 0, 18, 3        
    C dw 5 dup (?)              
    N dw 5                      
    
.code

start:
    mov ax,@data
    mov ds,ax

;   mov dx,offset A
;   push dx
;   mov dx, offset B
;   push dx
;   mov dx,offset C
;   push dx

    push offset A
    push offset B
    push offset C
    push N

    call arraysum

;   mov dx, offset A
;   push dx

    push offset A
    push N

    call printarray

    mov ah, 2
    mov dl, 10   
    int 21h

;   mov dx, offset B
;   push dx

    push offset B
    push N

    call printarray

    mov ah, 2
    mov dl, 10   
    int 21h

;   mov dx, offset C
;   push dx

    push offset C
    push N

    call printarray

    mov ah, 2
    mov dl, 10   
    int 21h

exit:
    mov ax,4c00h
int 21h

sum proc near
    push bp
    mov bp,sp
    mov ax,[bp+4]   
    add ax,[bp+6]
    pop bp
    ret                 
sum endp

arraysum proc near
    push bp
    mov bp, sp
    mov cx,[bp+4]           ;; num rep
    mov di, [bp + 10]       ;; off array A
    mov si, [bp + 8]        ;; off array B
    mov bx, [bp+6]          ;; off array C 

next:
    push word ptr [di]      ;; push elements A[i] and B[i], i = 0 .. 4
    push word ptr [si]
    
    call sum
    
    pop word ptr [si]
    pop word ptr [di]       
                          
    mov [bx], ax
    add si, 2  
    add di, 2  
    add bx, 2
    dec cx
    jnz next
    pop bp
    ret 8           
arraysum endp

printnum proc near
    push bp
    mov bp, sp
    mov ax, [bp + 6]            
    mov bx, 10
     
    mov cx, 0                   
    
    cmp ax, 0 
    jge next1
    neg ax
    
next1:   
    mov dx, 0
    div bx
    add dx, 30h
    push dx
    inc cx
    cmp ax, 0
    jne next1
    
    mov ax,[bp + 6]
    cmp ax, 0
    jge sof
     xor ax,ax
     mov al,'-'
    push ax
    inc cx
    
sof:
    cmp cx, 0
    jz ext
    pop dx
    mov ah, 2
    int 21h
    dec cx
    jmp sof
    
ext:
    pop bp
    
    ret         ;
printnum endp

printarray proc near
    push bp
    mov bp, sp
    mov cx, [bp + 4] 
    mov si, [bp + 6] 
    
print_loop:
    push word ptr [si]  
       push cx 
    call printnum
pop cx  
    add sp, 2          
    add si,2               
    dec cx     

    mov ah, 2
    mov dl, ' '   
    int 21h
    
    jnz print_loop     

    pop bp
    ret 4
printarray endp

end start