Sort 10 integer numbers read from keyboard and display in ascending order - arrays

Question

I managed to write this code for turbo debugger in assembly language which is meant to sort 10 integer numbers read from the keyboard and display them in ascending order but it keeps looping B to infinite..
The code is :
.model small
.stack 100h
.data
strg1 DB 'Insert numbers: $'
strg2 DB 'Sorted numbers: $'
Arr Db 10 dup(?)
v dw ?
.code
main proc
mov ax,#data
mov ds,ax
mov ah,9
lea dx,strg1
int 21h
mov dl,0ah
mov ah,2
int 21h
;inputs
mov di,0
mov cx,10
Input_loop:
mov ah,1
int 21h
mov arr[di],al
mov dl,0ah
mov ah,2
int 21h
inc di
loop Input_loop
mov v,0
sort:
mov di,0
mov cx,10
sub cx,v
B:
mov al,Arr[di]
cmp al,Arr[di+1]
jng C
mov al,Arr[di]
xchg al,Arr[di+1]
mov Arr[di],al
c:
inc di
loop B
inc v
cmp v,10
jne sort
;Output
mov ah,9
lea dx,strg2
int 21h
mov dl,0ah
mov ah,2
int 21h
mov di,0
mov cx,10
Output_loop:
mov dl,Arr[di]
mov ah,2
int 21h
inc di
mov dl,0ah
mov ah,2
int 21h
loop output_loop
mov ah,4ch
int 21h
main endp
end main
It is running perfectly, I can enter my desired numbers to be sorted, and then when it reaches c: , it just keeps looping B to infinite and it really makes me mad . Do you have any idea what went wrong and how can I fix it ?

Answer 1

Arr Db 10 dup(?)
v dw ?
In an array that has 10 elements, you can do 9 pairwise comparisons at most.
Your code does 10 comparisons and will move whatever byte is stored after the array, and that is probably a zero, down in memory!
Initialize v at 1:
mov v, 1
sort:
This is the only modification that I made and your program ran perfectly in DOSBox. I assembled the source using TASM 4.1 followed by TLINK
A better BubbleSort
Don't use BubbleSort, better algorithms exist! :-)=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Better use a register like SI instead of a memory based variable v.
Use downcounting for the outer loop count.
Because your elements are byte-sized, you can read and write two elements together.
Keep addressing modes simplest/shortest (using [di] instead of Arr[di]).
Avoid the slow LOOP instruction.
Use meaningful names for your labels.
Avoid using XCHG between a register and memory.
Use unsigned conditional jumps after comparing unsigned quantities like characters "0" to "9" (using jna instead of jng).
mov si, 10-1
Outer:
mov di, offset Arr
mov cx, si
Inner:
mov ax, [di]
cmp al, ah
jna Skip
xchg al, ah
mov [di], ax
Skip:
inc di
dec cx
jnz Inner
dec si
jnz Outer