/* ********************************************************************************
 * ECE 2045 Lab 3 Part3 Template 
 * This program displays a decimal digit on the 7-segment display HEX0. 
 * Pressing a KEY has the following result:
 * 	KEY 0. sets the display to 0
 * 	KEY 1. increments the displayed number
 * 	KEY 2. decrements the displayed number
 * 	KEY 3. sets the display to be "blank"
 ********************************************************************************/
		.text
		.global	_start
_start:		
		MOV		R4, #0		// counter value to be displayed on HEX0
		LDR		R5, =0xFF200050	// base address of KEY pushbuttons
		LDR		R6, =0xFF200020	// base address of HEX3_HEX0 7-segs
		STR		R4, [R6]	// clear the display

/* Continue your code from here;
 * Call the subroutine SEG7_CODE to show a decimal digit on HEX0
 */     


/* End your code here */
	
/* Subroutine to convert the digits from 0 to 9, or blank, to be shown on a HEX display.
 * Parameters: R0 = the decimal value of the digit to be displayed
 * Returns: R0 = bit patterm to be written to the HEX display
 */
SEG7_CODE:	
		MOV		R1, #0		// blank
DISPLAY0:
		CMP		R0, #0
        BNE		DISPLAY1
		MOV		R1, #0b0111111	// 0
        B 		END_SEG7
DISPLAY1:		
		CMP		R0, #1
        BNE		DISPLAY2
		MOV		R1, #0b0000110	// 1
        B 		END_SEG7
DISPLAY2:
		CMP		R0, #2
        BNE		DISPLAY3
		MOV		R1, #0b1011011	// 2
        B	 	END_SEG7
DISPLAY3:
		CMP		R0, #3
        BNE		DISPLAY4
		MOV		R1, #0b1001111	// 3
        B	 	END_SEG7	
DISPLAY4:
		CMP		R0, #4
        BNE		DISPLAY5
		MOV		R1, #0b1100110	// 4
        B	 	END_SEG7
DISPLAY5:
		CMP		R0, #5
        BNE		DISPLAY6
		MOV		R1, #0b1101101	// 5
        B	 	END_SEG7
DISPLAY6:
		CMP		R0, #6
        BNE		DISPLAY7
		MOV		R1, #0b1111101	// 6
		B	 	END_SEG7
DISPLAY7:
		CMP		R0, #7
		BNE		DISPLAY8
		MOV		R1, #0b0000111	// 7
		B	 	END_SEG7
DISPLAY8:
		CMP		R0, #8
		BNE		DISPLAY9
		MOV		R1, #0b1111111	// 8
		B	 	END_SEG7
DISPLAY9:
		CMP		R0, #9
		BNE		END_SEG7
		MOV		R1, #0b1100111	// 9
END_SEG7:
		MOV		R0, R1		// return bit pattern
		BX 		LR
		.end