; +----+----+----+
; | 11 | 10 | 9  | 	P0.3
; +----+----+----+
; | 8  | 7  | 6  | 	P0.2
; +----+----|----+
; | 5  | 4  | 3  | 	P0.1
; +----+----+----+
; | 2  | 1  | 0  | 	P0.0
; +----+----+----+
;  P0.6 P0.5 P0.4



;           A
;       ---------
;       |       |
;      F|       |B
;       |   G   |
;       ---------
;       |       |
;      E|       |C
;       |_______|
;           D
;
;   GFEDCBA
; #11000000B - 0
;   GFEDCBA
; #11111001B - 1
;   GFEDCBA
; #10100100B - 2
;   GFEDCBA
; #10110000B - 3
;   GFEDCBA
; #10011001B - 4
;   GFEDCBA
; #10010010B - 5
;   GFEDCBA
; #10000010B - 6
;   GFEDCBA
; #11111000B - 7
;   GFEDCBA
; #10000000B - 8
;   GFEDCBA
; #10010000B - 9

start:
	MOV R0, #0

	;first row
	CLR P0.0
	CALL cols_scan;
	SETB P0.0

	JB F0, display_num ;if found key in row 0,1,2 jump to display procedure



	;second row
	CLR P0.1
	CALL cols_scan;
	SETB P0.1

	JB F0, display_num ;if found key in row 3,4,5 jump to display procedure



	;third row
	CLR P0.2
	CALL cols_scan;
	SETB P0.2

	JB F0, display_num ;if found key in row 6,7,8 jump to display procedure



	;fourth row
	CLR P0.3
	CALL cols_scan;
	SETB P0.3;

	JB F0, display_num ;if found key in row 9,10,11 jump to display procedure


keep_scanning:
	jmp start








display_num:
	CLR F0
	MOV A, R0 	; move R0 (pressed number on keypad) to A, so we can divide
	MOV B, #10	; move 10 to B register
	DIV AB  ; divide A (pressed number on keypad) by 10 (value of B),
			; so if we have for example pressed 12 -> A:1 B:2 etc. reminder in B value of division in A

	MOV R0, A ; for later use


	CLR P3.4 ; choose display 0
	CLR P3.3 ; choose display 0
	MOV P1, #0FFH; clear the display

	mov A, B
	CALL num_in_A_to_display




	CLR P3.4  ; choose display 1
	SETB P3.3 ; choose display 1
	MOV P1, #0FFH; clear the display

	MOV A, R0
	CALL num_in_A_to_display


	jmp keep_scanning




num_in_A_to_display:
	CLR F0
	JZ num_0_to_display ;if zero in A, jump to procedure that puts 0 on display

	CLR C 				;clear carry flag, so it won't affect substracion
	SUBB A, #1  		;substract 1 from A, so if initailly A stored 1 it will be 0 now
	JZ num_1_to_display ;if A is zero now, jump to procedure that puts 1 on display

	CLR C
	SUBB A, #1  		;substract 1 from A, so if initially A stored 2, now is 1, because of previous substraction
	JZ num_2_to_display ;if A is 0 now (after second subtraction) jump to procedure that puts 2 on display

	;carry on as above up to 9
	CLR C
	SUBB A, #1
	JZ num_3_to_display

	CLR C
	SUBB A, #1
	JZ num_4_to_display

	CLR C
	SUBB A, #1
	JZ num_5_to_display

	CLR C
	SUBB A, #1
	JZ num_6_to_display

	CLR C
	SUBB A, #1
	JZ num_7_to_display

	CLR C
	SUBB A, #1
	JZ num_8_to_display

	CLR C
	SUBB A, #1
	JZ num_9_to_display

	RET


num_0_to_display:
	MOV P1, #11000000B;
	RET

num_1_to_display:
	MOV P1, #11111001B;
	RET

num_2_to_display:
	MOV P1, #10100100B;
	RET

num_3_to_display:
	MOV P1, #10110000B;
	RET

num_4_to_display:
	MOV P1, #10011001B;
	RET

num_5_to_display:
	MOV P1, #10010010B;
	RET

num_6_to_display:
	MOV P1, #10000010B;
	RET

num_7_to_display:
	MOV P1, #11111000B;
	RET

num_8_to_display:
	MOV P1, #10000000B;
	RET

num_9_to_display:
	MOV P1, #10010000B;
	RET

cols_scan:
	JNB P0.4, gotKey
	INC R0

	JNB P0.5, gotKey
	INC R0

	JNB P0.6, gotKey
	INC R0

	RET


gotKey:
	SETB F0 ; indicate found key by setting f0 flag
	RET