[SOLVED] Printing a triangle of characters in assembly

Printing a triangle of characters in assembly

I am developing this exercise:

write the assembler program that, given a character as input, outputs a triangle of size 5 x 5 of the character itself.

I have a problem because when I go to input a character, the characters do not form a triangle, but other characters are printed.

My input:

f

My output:

Desired output:

f
ff
fff
ffff
fffff

My code:

Title PROVA
;programma per la prova dell’ambiente Turbo Assembler 

DOSSEG
.MODEL SMALL
.STACK 100 
.DATA 
; se ci sono qui vanno dichiarate le vriabili

.CODE
  MOV AX, @data  ;(obbligatorie) inizializzano il DS      
  MOV DS, AX 
  
  MOV AX, 00
  MOV BX, 00
  MOV CX, 00
  MOV DX, 00

  mov ah,01h ;input va a mettere l'input in AL ;n
  int 21h
  MOV BL, AL ;n
  MOV CL, BL ;n
  
  MOV CH, 0H
  
  ciclo:
  CMP CH, 5H
  JE fine

  inc CH

  MOV DL, BL
  mov ah, 02h  ;stampa il contenuto di dl
  int 21h

  mov DL, 10D
  int 21h
  mov DL, 13D
  int 21h
  
  ;BL
  ADD BL, CL 
  
  JMP ciclo

  fine:
  MOV AL, 00H  ;(obbligatorie) ritornano il controllo al sistema operativo      
  MOV AH, 4CH 
  INT 21H 
 
END

Solution

As vitsoft pointed out, the char changed because you add CL to BL. To make a triangle you need to use another loop, as Michael said. Below is the part to change:

  MOV   AH, 01h  ; input va a mettere l'input in AL ;n
  INT   21H
  MOV   BL, AL   ; n
  
  MOV   CH, 0H
ciclo:
  CMP   CH, 5H
  JE    fine
  INC   CH
  
  MOV   DL, 10D
  INT   21H
  MOV   DL, 13D
  INT   21H
  
  MOV   CL, CH
  MOV   AH, 02H  ; stampa il contenuto di dl
  MOV   DL, BL
innerLoop:
  INT   21H
  DEC   CL
  JNE   innerLoop

  JMP ciclo

fine: