Assembly 8086 - How to insert string buffer into another string buffer?

Question

I'm making a program, which instead of "1bc" writes "ONEbc". However, I'm struggling to insert one string inside another. I managed to do that the program changes each char, but I need to insert a whole string, not symbol by symbol, while also my program doesn't print the rest of the text (just "ONE"). This is the segment which changes 1 into ONE.

.DATA
        one db "ONE" ; I want to include this into my code somehow

**************************************************

    MOV cx, ax
    MOV si, offset firstBuf ; (firstBuf db "1bc")
    MOV di, offset newBuf ; (should be "ONEbc" after this)
  work:
    MOV dl, [si]
    CMP dl, '1'
    JNE continue  
        ADD ax, 3     
    MOV cx, ax
    MOV [di], 'O'
    INC si
    INC di
    MOV [di], 'N'
    INC si
    INC di
    MOV [di], 'E'   
    JMP next
  continue: 
    MOV [di], dl   
  next:
    INC si
    INC di
    LOOP    work

As you can see, I have tried putting the string symbol by symbol, but I think there's a better way to do that. I'm a beginner and I'm using emu8086, if that helps.

Answer 1

The output didn't show "bc" because of the 2 additional increments on the SI register! And changing CX in the middle of the loop will cause reading past the source string, so don't do that either.

    MOV cx, ax       ; Length of the input string
  work:
    MOV dl, [si]
    INC si
    CMP dl, '1'
    JNE continue  
    ADD ax, 2        ; New length of the output string we're building
    MOV [di], 'O'
    INC di
    MOV [di], 'N'
    INC di
    MOV dl, 'E'   
  continue: 
    MOV [di], dl
    INC di
    LOOP    work

I have tried putting the string symbol by symbol, but I think there's a better way to do that.

You can output 2 characters together:

    MOV cx, ax       ; Length of the input string
  work:
    MOV dl, [si]
    INC si
    CMP dl, '1'
    JNE continue  
    ADD ax, 2        ; New length of the output string we're building
    MOV word [di], 'ON'
    ADD di, 2
    MOV dl, 'E'   
  continue: 
    MOV [di], dl
    INC di
    LOOP    work

You could also retrieve the "ONE" string from somewhere else. Especially interesting if the text to insert is somewhat longer.

    MOV cx, ax       ; Length of the input string
  work:
    MOV dl, [si]
    INC si
    CMP dl, '1'
    JNE continue  
    mov bx, OFFSET one
    mov bp, 2
    add ax, bp        ; New length of the output string we're building
nestedLoop:
    mov dl, [bx]
    inc bx
    mov [di], dl
    inc di
    dec bp
    jnz nestedLoop
    mov dl, [bx]
  continue: 
    MOV [di], dl
    INC di
    LOOP    work