; File: strout.asm
; Written By: Deepak Kumar
; Date: March 25, 2024
; Purpuse:
;   To show how to write your own version of LC-3's PUTS
;   Given the address of a string in R0, output the string.
;   The string has to be null terminated.
;
; The main program
;
; First, the string to be output
        .ORIG x3000
HELLO   .STRINGZ    "\nHello, world!\n"
;
; Next, the main program
;
START   LEA     R0, HELLO
        JSR     STROUT
DONE    HALT
;
; The PUTSTR subroutine
; STROUT
; Given the starting address of a string in R1
; Output the string to console
;
STROUT  
        ST      R1, SaveR1
        ADD     R1, R0, #0      ; Copy R1 into R0 (since R0 is used for char output)
LOOP    LDR     R0, R1, #0
        BRz     STROUTDONE
        OUT
        ADD     R1, R1, #1
        BR      LOOP
STROUTDONE
        LD      R1, SaveR1
        RET
SaveR1  .BLKW   1
        .END