LimitedRandomValues(0-5).asm

; assembly code that takes user input and creates
; a set of random numbers if called repeatedly using for example
; a loop.

section .data
seedMsg db "Put in 8 characters to act as the basis for random value: " ;Ask the user to put in 8 characters, for example their name
seedMsgLen equ $-seedMsg ; Get the length of the message
section .bss 
  num1 resb 8 ; variable to store random number 
  seed resb 8 ; variable to store random number seed
section .text
  global _start
  _start
  mov rax,4 ;; Move the system call 4 to the register rax 
  ; to say name question
	mov rbx,1 ;;  put the value 1 in the register rbx - 
	; standard output to the screen
	mov rcx, seedMsg ; Put the offset of name in rcx register 
	;; so we can access the string 'name'
	mov rdx, seedMsgLen ;Move length of name in register
	int 80h ; Call the operating system with an interrupt. 
  
  mov rax,3 ; system call input
  mov rbx, 0 ; stand input
  mov rcx, seed ; store inputted value in answer - note ascii 
	; value and should be a name of up to 6 characters
  mov rdx, 8 ; size of input value in bytes
  int 80h ; interrupt
  mov rax, [seed] ; put the name into the register
  call random ; call random
  call random ; call random
  call end ; call end
; random function
random:
  xor rdx,rdx ; ensure that rdx is empty to stop overflow
  mov rbx, 6 ;To get 0 to 5 move 6 into 
  div rbx ;Div rax by rbx put remainder in rdx
  add rdx, '0' ; make remainder ascii to print
  push rax ; put rax on the stack
  mov [num1], rdx ; put ascii remainder in num1
  mov eax,4 ; system call print to screen
  mov ebx, 1 ; standard out 
  mov ecx, num1 ; ascii remainder
  mov edx, 1 ; size of output
  int 80h ; interrupt
  pop rax ; pop off stack
  shr rax, 1 ; shift the binary value right by one 0101101 becomes 0010110.  To make more random can use shl (shift left) vary the number of digits moved
  ret ; return
; end function
end:
  mov eax, 1 ; exit system call
  int 80h ; interrupt