Search for and replace characters in a string in assembly nasm issues -

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i've got working copies string another. i'm trying make search term , swap it. reason, if replace function isn't commented, somehow manages delete output in console (literally goes backwards!). if comment replace function out, exact copy. trying change cat dog. 

    bits 64     global main     extern printf      section .text main:     ; function setup     push    rbp     mov     rbp, rsp     sub     rsp, 32     ;     lea     rdi, [rel message]     mov     al, 0     call    printf      ;print source message     lea     rdi, [rel source]     mov     al, 0     call    printf      ;print target message     lea     rdi, [rel target]     mov     al, 0     call    printf        lea rdi, [rel target]     lea rsi, [rel source]     cld     jmp loop  loop:     lodsb       ;load byte @ address rsi al     stosb       ;store al @ address rdi     ;push   [rdi]        cmp byte rdi, 'c'     je  replace          ;pop [rdi]     test al,al  ;code jump if al not equ 0     jnz loop  replace:     ;lea     rdi, [rel success]     mov byte [rdi], 'd'     ;call    printf       ret      ;print new version of target     lea     rdi, [rel target]     mov     al, 0     call    printf    ; function return mov     eax, 0 add     rsp, 32 pop     rbp ret  section .data message: db      'project:',0x0d,0x0a,'author:',0x0d,0x0a,0x0d,0x0a,0  source:  db "the cat chased bird.",0x0a,0x0d,0 target:  db '0000000000000000000000000000000000000000000',0x0d,0x0a,0  success: db "success",0

this want. tested in ubuntu 64 with: (assumed file a.asm)

nasm -f elf64 -l a.lst a.asm & gcc -m64 -o a.o

bits 64 global main extern printf  section .text main: ; function setup push    rbp mov     rbp, rsp sub     rsp, 32 ; lea     rdi, [rel message] mov     al, 0 call    printf  ;print source message lea     rdi, [rel source] mov     al, 0 call    printf  ;print target message lea     rdi, [rel target] mov     al, 0 call    printf  lea rdi, [rel target] lea rsi, [rel source] cld  loop:  lodsb       ;load byte @ address rsi al stosb       ;store al @ address rdi  cmp  al, 'c' jne  loopback  lodsb       ;load byte @ address rsi al stosb       ;store al @ address rdi cmp  al, 'a' jne  loopback  lodsb       ;load byte @ address rsi al stosb       ;store al @ address rdi cmp  al, 't' jne  loopback  sub rdi, 3 mov byte [rdi], 'd' inc rdi mov byte [rdi], 'o' inc rdi mov byte [rdi], 'g' inc rdi  loopback: cmp al, 0 jne loop  ;print new version of target lea     rdi, [rel target] mov     al, 0 call    printf  ; function return mov     eax, 0 add     rsp, 32 pop     rbp ret  section .data message: db      'project:',0x0d,0x0a,'author:',0x0d,0x0a,0x0d,0x0a,0  source:  db "the cat chased bird.",0x0a,0x0d,0 target:  db '0000000000000000000000000000000000000000000',0x0d,0x0a,0  success: db "success",0

the output this:

project: author:  cat chased bird. 0000000000000000000000000000000000000000000 dog chased bird.

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