removespaces

.model small
.stack 100h
.data
s   db  'Hello,     wo r  ld!',0 ; null-terminated z-string
len equ $ - s ; need for buffer allocation
buf db len dup(0)
buflen db len
char db ' ' ; remove whitespaces

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

    lea di, s
    mov al, char
    mov ah, 0
    xor dx, dx
    xor bx, bx


cycle:
check_end_of_string:
    cmp [di], 0
    je end_cycle
check_char:
    cmp al, [di]
    jne copy
check_first:
    cmp ah, 0 ; if ah == 0, then it's first occure-in-a-row of symbol
    mov ah, 0
    jne cycle_increment

copy:
    mov ah, 1
    mov dl, [di]
    push dx
    inc bx
cycle_increment:
    inc di
    loop cycle


 end_cycle:


    mov buflen, bl

    lea di, buf
    mov cx, bx
    std

make_str:
    pop ax
    stosb
    loop make_str

output_str:
    mov ah, 40h
    mov bx, 1
    mov dx, di
    mov cl, buflen
    int 21h
exit:

    mov ax, 4C00h
    int 21h

end start