CODEWITHSUNDEEP
x86assembly
user573382
user573382

Reputation: 343

(emu8086) multiplying 3x3 matrix with array

if anyone knows assembler language i'd really need some help debugging my program. I have a 3x3 matrix and a 3 element vector that i read from the console, and i need to multiply them and display the resulting array.

This is my code so far:

name "2x2_matrix"
include "emu8086.inc"
org 100h ; directive make tiny com file.


.model small
.stack 100h
.data

size    dw      3  
A       db      ?,?,?,?,?,?,?,?,?     
B       db      ?,?,?
C       db      ?,?,?

message_a db 10,13,"type the elements of matrix A:$"
message_b db 10,13,"type the elements of array B:$"
rez db 10,13,"the result is:$"     

.code 
start: 
mov ax,@data
mov ds,ax

mov bx, 0  ; 

 read_a: 
;compare with sizexsize
mov ax, size
mul size
cmp bx, ax
je reset_counter

;display message
mov dx, offset message_a
mov ah, 09h
int 21h

;read element
mov ah, 01h
int 21h
sub al, 30h
mov A[bx], al

inc bx
jmp read_a

reset_counter:
mov bx, 0        
jmp read_b    

read_b:  
;compare with size
mov ax, size
cmp bx, ax
je calcul

;display message
mov dx, offset message_b
mov ah, 09h
int 21h

;read element
mov ah, 01h
int 21h
sub al, 30h
mov B[bx], al

inc bx
jmp read_b

calcul:
mov bx,0 
mov cx,0  

for_i:       
    mov ax, size
    cmp bx, ax
    je print 

    mov al,b.size
    mul bx

    mov al, A[bx+1]
    mov bh, B[bx+1]
    mul bh
    add C[bx], ah

    mov al, b.A[bx+2]
    mov bl, b.B[bx+2]
    mul al
    add C[bx], ah

    mov al, b.A[bx+3]
    mov bl, b.B[bx+3]
    mul al
    add C[bx], ah

    inc bx
    jmp for_i               

print:

mov dx, offset rez
mov ah,09h
int 21h

mov     ax,size
mul     size
mov     cx,ax
mov     ax,0
mov     bx,0

print_c:

    cmp     bx,cx
    je      finish

    mov     al, C[bx]
    CALL    PRINT_NUM

    inc     bx
    jmp     print_c

DEFINE_PRINT_NUM
DEFINE_PRINT_NUM_UNS

finish:
ret

end start

end

It seems to loop and not display anything after i insert the elements, and i'm not sure how to debug it. If anyone is familiar with assembler-type coding and can help me fix my code i'd greatly appreciate it!

Upvotes: 0

Views: 6520

Answers (1)

Osiris76
Osiris76

Reputation: 1244

By reading the provided code I found some strange lines:

mov bh, B[bx+1]
mul bh

Here you assign the register bh (and ultimately bx too) a new value to be multiplied to ah. But you also use bx as the index of your result array. It seems to me as if you change your array index while calculating the necessary information.

The same goes for the following lines

mov al, b.A[bx+2]
mov bl, b.B[bx+2]
mul al
add C[bx], ah

mov al, b.A[bx+3]
mov bl, b.B[bx+3]
mul al
add C[bx], ah

But here you should be aware that you multiply al with al which I assume is not the desired operation.

As a solution you could rename every occurence of bh or bl to dh/dl or ch/cl and change the factor in the multiplication accordingly. Then the index remains the same and the loop will work.

Upvotes: 1

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