LC3 input loop

gistfile1.txt

Just the commments.  ValidateOne should also be called ifone or something.  



.ORIG x3000; 

;REGISTER ASSIGNMENT INFORMATION
	; R0 is I/O
	; R1 manages the address of the storage memory for the first loop
	; R2 is a temporary variable
	; R3 is used as a Counter here for the first loop
	; R4 is counter for the number of zeros
	; R5 temp variable for subtraction 
	; R6 is 48 throughout program
	; R7 is used for Subroutines

LEA R1 MEMORYSPACE ; Saves the address of the storage memory block
LD R3 COUNTER      ; Declare counter for input loop
LD R5 SUB48        ; Load R5 with -48
LD R6 ADD48        ; Load R6 with  48 

LEA R0 PROMPT;
PUTs;

Input loop just grabs the 16 bit binary number


INPUTLOOP; 
    	GETC                	; Input character -> r0
     	ADD R0 R5 R0        	; Subtract 48 here to get actual value of the digit
    	
    	if the input here was a zero, then increment the 0 counter
    	BRz IFZERO          	; If zero, know it's a good binary input, skip validate for one
	    this validate one thing here is like, if it is a zero it skips it bc we good.  So only other option is a 1.  
	    if it's not a one then it's not a valid input
	    JSR VALIDATEONE		    ; Just checked for a zero, only other possibility is a one for valid input. Validates here
	    RESUMEINPUT	          ; If went to zero statement, resume loop here   
    
	    STR R0 R1 #0        	; r0 -> ( memory address stored in r1 + 0 )
    	ADD R1 R1 #1        	; increments the memory pointer so that it always points at the next available block
    	ADD R3 R3 #-1		      ; decrement loop counter    
BRp INPUTLOOP			; loop until 16 to get full 16 bit binary string

IFZERO;
	;  Increment zero counter
  	;   Branch to skip input validation, we already know the input was a 0, Ask about jsrr
  

VALIDATEONE; 			If it's a zero it would have been skipped already, so just need to make sure that the value is a 1
	; Clear R2, to make room for entered number currently in R0
 	; ADD R0 value to R2 for manipulation
	; Subtract 1 from R2 value
	; If value is zero then the value was a one, skip mistake prompt

	;mistake prompt starts here
		; Save R0 value into TEMP label
		; Output mistake prompt, let the user they need to enter only binary
		;   
		;
		;
		;Reload R2 value into R0, which is the io value that was entered
		;Skip to here if iunput was one or a zero
RET;

;LABELS
	COUNTER 	.FILL  16;
	MEMORYSPACE 	.blkw  16;
	SUB48 		.FILL -48;
	ENTER        	.FILL x000A;
	TEMP2           .FILL x3155; 
	MASK 		.FILL x8000;  1000 on first grouping grabs Most Sig Dig
	ORIGINAL 	.FILL x3050;
	ROTATED 	.FILL x3002;
	TEMP 		.FILL x3100;  
	AMOUNT 		.FILL x3113; 
	NEWLINE     	.STRINGZ "\n";
	PROMPT3    	.STRINGZ "Rotated:  \n"; 
	MISTAKE 	.STRINGZ "\nEnter a 1 or 0 character!\n"
	ORIGPROMPT 	.STRINGZ "Enter a 16-bit binary number to rotate: \n";
	AMNTPROMPT 	.STRINGZ "\nEnter a number from 0-16. Single digit must have a '0' in front of it.\n";
	.END