LC3 Funzies

.ORIG x3000
AND R0, R0, #0 ;initialize all registers to 0, except for R7
AND R1, R1, #0
AND R2, R2, #0
AND R3, R3, #0
AND R4, R4, #0
AND R5, R5, #0
AND R6, R6, #0

LD R1, User_Char ;load variables
LD R2, This_Digit
LD R3, Neg_Flag
LD R4, User_Int

LEA R0, STARTPROMPT ;print welcome message
PUTS
GET_USER_CHAR AND R0, R0, #0 ;clear R0 for GETC
GETC
AND R0, R0, #0

BRzp XCHECK
	ADD R3, R3, #1 ;Neg_Flag=1
	BR GET_USER_CHAR

XCHECK ADD R1, R1, R0
ADD R1, R1, #-16 ;Subtract 88 (X) from ASCII value in R1
ADD R1, R1, #-16
ADD R1, R1, #-16
ADD R1, R1, #-16
ADD R1, R1, #-16
ADD R1, R1, #-8

BRz GOODBYE ;Exit the program if entered character was X
	AND R1, R1, #0 ;Subtract 12 (Newline) from ASCII value in R1
	ADD R1, R1, R0
	ADD R1, R1, #-12
	BRz 2SC_CHECKER ;Converts User_Int into 2SC if newline was entered

AND R1, R1, #0
ADD R1, R1, R0
ADD R1, R1, #-16 ;Subtract "0" in ASCII from inputted value
ADD R1, R1, #-16
ADD R1, R1, #-16
ADD R2, R1, #0 ;Update This_Digit
ADD R4, R4, R4 ;User_Int*10
ADD R4, R4, R4
ADD R4, R4, R4
ADD R4, R4, R4
ADD R4, R4, R1 ;User_Int=User_Int*10+This_Digit

BR GET_USER_CHAR
	2SC_CHECKER ADD R3, R3, #0

BRz PRINT_USER_INT_LOOP ;If Neg_Flag is not set, print the User_Int, otherwise take 2SC of User_Int
	NOT R4, R4
	ADD R4, R4, #1

PRINT_USER_INT_LOOP AND R0, R0, #0
	ADD R0, R0, R5 ;Copy Counter_Offset to R0, check whether 16 iterations passed
	ADD R0, R0, #-15
	ADD R0, R0, #-1

	BRz GET_USER_CHAR ;program returns to prompt after printing inputted number in binary
		AND R0, R0, #0
		AND R6, R6, #0 ;clears previous bit mask retrieved from Mask_Array
		LEA R6, Mask_Array ;store Mask_Array pointer in R6
		ADD R6, R6, R5 ;add offset of Counter_Offset to Mask_Array pointer
		LDR R0, R6, #0 ;Load array value at new position into R0
		AND R0, R0, R4 ;Look at specific bit of User_Int

		BRnp ONE
			AND R0, R0, #0 ;Resets R0 to be used for printing 1
			LD R0, Zero
			PUTC
			BR INCREMENT

			ONE AND R0, R0, #0 ;Resets R0 to be used for printing 0
			LD R0, One
			PUTC

		INCREMENT ADD R5, R5, #1 ;Increments Counter_Offset
		BR PRINT_USER_INT_LOOP

GOODBYE AND R0, R0, #0
LEA R0, ENDPROMPT ; prints exit message
PUTS
HALT

STARTPROMPT .STRINGZ "Welcome to the conversion program!"
ENDPROMPT .STRINGZ "Bye. Have a great day."
User_Char .FILL #0
This_Digit .FILL #0
Neg_Flag .FILL #0
User_Int .FILL #0
Mask_Array:
.FILL b1000000000000000
.FILL b0100000000000000
.FILL b0010000000000000
.FILL b0001000000000000
.FILL b0000100000000000
.FILL b0000010000000000
.FILL b0000001000000000
.FILL b0000000100000000
.FILL b0000000010000000
.FILL b0000000001000000
.FILL b0000000000100000
.FILL b0000000000010000
.FILL b0000000000001000
.FILL b0000000000000100
.FILL b0000000000000010
.FILL b0000000000000001
.END