ej2_prefijo.asm

CHAR_SIZE equ 1

section .text

extern strcpy

global prefijo_de
global quitar_prefijo


;rsi = char* str2
;rdi = char* str1

prefijo_de:
   push rbp
   mov rbp, rsp

   xor rax, rax

   .while:
      mov cl, [rdi]
      mov dl, [rsi]

      test cl, cl
      jz .end

      test dl, dl
      jz .end

      cmp cl, dl
      jne .end

      inc rsi
      inc rdi
      inc rax

      jmp .while

   .end:
   mov rsp, rbp
   pop rbp
   ret



;rsi = char* str2
;rdi = char* str1

quitar_prefijo:
   push rbp
   mov rbp, rsp
   sub rsp, 16
   push r8
   push r9
   
   mov [rbp - 8], rsi ; str2
   mov [rbp - 16], rdi ; str1
   
   call prefijo_de
   mov r8, rax 
   
   call strlen
   mov r9, rax 

   sub r9, r8 
   add r9, 1
   
  ;r8 = longitud_prefijo
  ;r9 = res_size 

   mov rax, CHAR_SIZE
   imul r9
   
   mov rsi, rax
   call malloc 
   
   mov rsi, rax
   mov rdi, [rbp - 8]
   add rdi, r8

   call strcpy

   pop r9
   pop r8
   mov rsp, rbp
   pop rbp
   ret