; #########################################################################################
; # Indiana University                                                                    #
; # Computer Science Department                                                           #
; #                                                                                       #
; # Example Program 3                                                                     #
; #                                                                                       #
; # DESCRIPTION:                                                                          #
; #                                                                                       #
; # This is a simple program to get two 2-digit decimal numbers from the terminal,        #
; # convert the numbers from ASCII to decimal, add the numbers, convert the result from   #
; # decimal to ASCII, and display the result on the terminal.                             #
; #                                                                                       #
; # AUTHOR:                                                                               #
; # Bryce Himebaugh (bhimebau@cs.indiana.edu)                                             #
; # IUCS Staff                                                                            #
; # 6/21/99                                                                               #
; #                                                                                       #
; #########################################################################################
	XREF STKTOP,Send_String,Get_Number,Output_Result
        
	SECTION code
START:  	
        move.l #STKTOP,sp                  ; setup the stack pointer
        movem d2,-(sp)                     ; save the entry value of d2 on the stack
        clr.l d2                           ; clear d2 to store the result of the calc.

        lea clear_screen_string,a0         ; place the starting address of string in a0
        jsr Send_String                    ; send the string to the terminal

        lea position_cursor,a0             ; place the starting address of string in a0
        jsr Send_String                    ; send the string to the terminal

        lea banner,a0                      ; place the starting address of string in a0
        jsr Send_String                    ; send the string to the terminal

        lea prompt1,a0                     ; place the starting address of string in a0
        jsr Send_String                    ; send the string to the terminal

        jsr Get_Number                     ; go get the first number from the terminal
        move.b d0,d2                       ; save the number received in D2. 

        lea add_symbol,a0                  ; place the starting address of string in a0
        jsr Send_String                    ; send the string to the terminal

        lea prompt2,a0                     ; place the starting address of string in a0
        jsr Send_String                    ; send the string to the terminal

        jsr Get_Number                     ; go get the second number from the terminal
        add.b d0,d2                        ; add the second number to the first

        lea calc_bar,a0                    ; place the starting address of string in a0 
        jsr Send_String                    ; send the string to the terminal

        lea prompt3,a0                     ; place the starting address of string in a0
        jsr Send_String                    ; send the prompt

        move.b d2,d0                       ; place result in d0 to send it to the term 
        jsr Output_Result                  ; send the result to the terminal

        movem (sp)+,d2                     ; restore the original value of d2
        clr.b d1                           ; prepare to use TRAP #15 to end the program 
        trap #15                           ; execute program termination 

        SECTION data

clear_screen_string:
        dc.b "\x1b[2J\x00"      ; String required by terminal to clear the screen 
position_cursor: 
        dc.b "\x1b[1;1f\x00"    ; String required by terminal to position the cursor @ 1,1
                                ; where the screen is row;col
                                ; Upper left corner   1, 1
                                ; Lower right corner 24,80 
add_symbol:
        dc.b "\n\r                           +\n\r\x00"
calc_bar:
        dc.b "\n\r                          --\n\r\x00"
banner:
        dc.b "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n\r"
        dc.b "%  This is a small program that adds two 2-digit decimal numbers. %\n\r"
        dc.b "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n\r\n\r\x00"                                                                  
prompt1:
        dc.b " First 2-Digit Number ->  \x00" 
prompt2:
        dc.b "Second 2-Digit Number ->  \x00"
prompt3:
        dc.b "               Result -> \x00"