; main.asm
;
; A simple program to write to standard output (stdout) and read from standard input (stdin)
;
; (C) 2017, Richard Marks <ccpsceo@gmail.com>
; MIT License
;
global start
stdout equ 1
stdin equ 0
sys_exit equ 0x2000001
sys_write equ 0x2000004
sys_read equ 0x2000003

section .text
start:
  mov rax, sys_write
  mov rdi, stdout
  mov rsi, login_msg
  mov rdx, login_msg.len
  syscall

  mov rsi, username
  call read_string

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, lf
  mov rdx, 1
  syscall

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, password_msg
  mov rdx, password_msg.len
  syscall

  mov rsi, password
  call read_string

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, lf
  mov rdx, 1
  syscall

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, welcome_msg
  mov rdx, welcome_msg.len
  syscall

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, username
  mov rdx, 0xff
  syscall

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, lf
  mov rdx, 1
  syscall

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, entry_msg
  mov rdx, entry_msg.len
  syscall

  mov rax, sys_write
  mov rdi, stdout
  mov rsi, password
  mov rdx, 0xff
  syscall

  mov rax, sys_exit
  mov rdi, 0
  syscall

; proc read_string (char* destination)
; use:
;   mov rsi, {buffer}
;   call read_string
read_string:
  mov rax, sys_read
  mov rdi, stdin
  ; mov rsi, buffer
  mov rdx, 0xff
  syscall
  ret

section .bss
buffer: resb 0xff
username: resb 0xff
password: resb 0xff

section .data

lf: db 0xa

login_msg: db 'login: '
.len equ $ - login_msg

password_msg: db 'password: '
.len equ $ - password_msg

welcome_msg: db 'welcome, '
.len equ $ - welcome_msg

entry_msg: db 'your password is '
.len equ $ - entry_msg