; Computer Architectures (02LSEOV)
; Problem n. 2
;https://911programming.wordpress.com/2010/05/14/emu8086-read-a-string-from-keyboard/
;http://www.fysnet.net/kbbuffio.htm
;https://eclass.upatras.gr/modules/document/file.php/EE649/8086%20Registers.htm
    DIM EQU 40h;64 bytes
    MIN_L EQU 14h; 20 chars min
    MAX_L EQU 32h;50 chars max
    CAE_K EQU 03h;Caesar cipher K
.MODEL small
.STACK
;;data segment: it will contain the four arrays
.DATA
    FIRST_ROW 	DB DIM DUP(?)
    SECOND_ROW 	DB DIM DUP(?)
    THIRD_ROW 	DB DIM DUP(?)
    FOURTH_ROW 	DB DIM DUP(?)
    prompt_str DB 'Please enter a string:$'
    oob_str DB 'Input out of bounds!$'
;;code segment
.CODE
.STARTUP
;;Prepare buffers: buffer[0] must be equal to buffer size.
	mov AH, DIM
	mov FIRST_ROW[0], AH
	mov SECOND_ROW[0], AH
	mov THIRD_ROW[0], AH
	mov FOURTH_ROW[0], AH
;;Acquire inputs
	lea DX, FIRST_ROW;get address of first row in DX
	call input_row
	call print; print first row
.EXIT

;;Inputs acquired.
;retrieves user input into a buffer, which is passed as the argument
; input_row( DX = buffer,  )
PROC input_row	NEAR
	push BP
	mov SP, BP
	push AX
	push BX
	push SI
	;print input prompt
	lea DX, prompt_str
	call print
	;initialize counter for input'd chars to 0
	mov CL, 0
	;use SI as base address for the string
	mov SI, DX
	;use BX as a pointer from the base address of the string
	mov BX, 0
	;INT 21 AL 1: get single char, then display it
input_loop:
	mov AH, 1
	INT 21h;result is stored in AL
	;Check it is not return
	;Which would indicate the end of input
	cmp AL,13; 13 = RETURN
	je check_length
	;Store input'd character in the string
	mov [SI][BX], al
	;Move the pointer 1 position forward
	inc BX

check_length:
input_row_end:
    pop SI
    pop BX
    pop AX
	pop BP
	ret
	;return values
	;1st byte of the buffer = buffer size
	;2nd byte of the buffer = string length (input'd characters)
ENDP
;prints a string.
; print( DX = buff )
PROC print NEAR
	push bp
	mov sp, bp
	push ax
	mov ah, 9
	int 21h
	pop ax
	pop bp
	ret
ENDP
END