NASM Assembly Question regarding to searching for a substring

Question

Hi guys so Im trying to write this code that checks if a character is in an inputted string. This is my code

I have written print statements to see how my program is running but it prints absolutely nothing.

extern getchar
extern printf
extern strlen
extern strchr


SECTION .data

    string1: db 0,0,0,0,0,0,0,0,0,0,0,0
  string2: db "it is there",10,0
  string3: db "not there",10,0
  string4: db "welp",10,0
  char:    db  "t",10,0
    count: dq 12
    forcount: dq 12 
  
    fmt: db "%s", 10, 0
  ;fmt2: db "%s", 10, 0

SECTION .text
global main
main:
SECTION .text
global main
main:
    sub     rsp, 32             ; shadow space

    mov     rdi, string1        ; printing to
    cld                         ; clear direction flag

.while:
    cmp     qword [count], 0    ; only get a char while counter is > 0
    jne     .continue
    jmp     .done
.continue:
    mov     rax, 0              ; clear rax before we get a char
    call    getchar
    cmp     eax, 10             ; newline
    jne     .continue2          ; stop collecting on new lines
    jmp     .done
.continue2:
    stosb                       ; puts al into [rdi] and then increments rdi
    sub     qword [count], 1
    jmp     .while
.done:
    mov     byte [rdi+1], 0     ; don't forget to 0 terminate your strings
    ;lea        rdx, [string1]                                                             ;it is here so fa
    ;lea        rcx, [fmt]
    ;call   printf
    

    
      lea rsi, [string1]
    lea rcx, [string1]
    call strlen
    
    lea rcx, [rax - 1] ; we need to decrement rax by 1 since strings are 0 indexed
    add rsi, rcx ; index to end of string (- 1)
    std ; auto decrement rsi
      mov   rdx, [string1]
   lea   rcx, [fmt]            ; a fmt string containing %lld
   call  printf  


;using it
mov    rcx, string1
mov    rdx,[char]
call     strchr

sub    rax, rcx 

cmp   rax, 0x00
je       .no    
jne     .yes 
jmp   .welp
 

 
.yes:
    mov   rdx, [string2]
   lea   rcx, [fmt]            ; a fmt string containing %lld
   call  printf    
.no:
 mov   rdx, [string3]
   lea   rcx, [fmt]            ; a fmt string containing %lld
   call  printf  

.welp:
 mov   rdx, [string4]
   lea   rcx, [fmt]            ; a fmt string containing %lld
   call  printf  

I have written **all this code ** and its not printing. Can someone please tell me what Im doing wrong here? Please tell me if you want me to rephrase the question

Answer 1

std                   ; auto decrement rsi
mov   rdx, [string1]
lea   rcx, [fmt]      ; a fmt string containing %lld
call  printf

Given that you're coding for NASM, loading the address of the string1 needs to become:

mov rdx, string1

This is an error that you repeat numerous times in your program!!!

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Also note that it's never a good idea to call any library function with the direction flag set. Many codez expect the direction flag to be clear.
Moreover, your current program doesn't use that set direction flag anyway.

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Where is your program exit?
Why are there 2 SECTION .text declarations?
...