/* Now that you have the source file in the screen editor, let`s use some of */
/* the edit commands available to us.  Referring to the source listing in    */
/* Chapter 2 of the I2ICE System User's Guide, we see that the first errors  */
/* we encountered were in the GET_INPUT procedure at lines 70 and 71.        */
/*                                                                           */
/* Let`s use the FIND edit command to locate the first error.  In our case,  */
/* VALUE is used several times, so we will need more than just the word VALUE*/
/* to identify the line we want.  Move the cursor to the start of the source */
/* listing.  Type F (for FIND).  The editor will prompt:  FIND"".   Enter the*/
/* string you want to find:                                                  */
/*     VALUE = VALUE + CHAR - '0' <ESC>                                      */
/* <ESC> is used to terminate this command.  Some edit commands do not       */
/* require you to press the <ESC> key after entering a command.  When <ESC>  */
/* is required to execute a command, it will be shown next to the command in */
/* brackets (< >).                                                           */
/*                                                                           */
/* NOTE:  Enter the string exactly as shown.  The editor is searching for an */
/* exact match.  If the editor does not find the string, it will display the */
/* following message (at the bottom of the screen):                          */
/*     not found: "name-of-the-string-you-are-searching-for"                 */
/*                                                                           */
$title('===>  Change Maker Demo  <===')

Cmaker: DO;

DECLARE
	TRUE literally '0FFH',
	FALSE literally '0',
	IN_PORT literally '1',
	OUT_PORT literally '2',
	lf_cr (2) BYTE DATA (0AH, 0DH),
	paid_text (*) BYTE DATA (7, 'Paid = '),		
	purchased_text (*) BYTE DATA (8, 'Price = '),		
	coins		WORD,
	change		WORD,
	dollars 	WORD,
	quarters	WORD,
	nickels		WORD,
	dimes		WORD,
	pennies		WORD,
	paid		WORD,
	purchased	WORD;

$eject

	read: PROCEDURE BYTE;  /*Sets char equal to ASCII byte received*/
		DECLARE            /*from port 1; writes byte to output port*/
			char BYTE;     /*also*/

		char = INPUT(in_port);
		RETURN char;
	END read;

	write: PROCEDURE (text_ptr, text_cnt); /*Writes text_cnt ASCII bytes */
		DECLARE                            /*that begin at txt_ptr to port2*/
			text_ptr POINTER,
			text_cnt WORD,
			text BASED text_ptr (1) BYTE,
			i WORD;

		DO i = 0 TO text_cnt - 1;       
			OUTPUT(out_port) = text(i);
		END;
	END write;

	write_decimal: PROCEDURE (value);/*Stores decimal digits in the array*/
		DECLARE                      /*digit_stack; calls for their conver-*/
			value WORD,              /*sion to ASCII*/
			i WORD,
			digit_stack(5) BYTE,
			stk_top WORD;

		stk_top = 5;
		DO WHILE value > 0;
			digit_stack(stk_top := stk_top - 1) = value MOD 10;
			value = value/10;
		END;
		DO i = stk_top TO 5;
			CALL convert_decimal_digit(digit_stack(i));
		END;
	END write_decimal;

	convert_decimal_digit: PROCEDURE (decimal_digit);/*Converts decimal digit*/
		DECLARE                                      /*to ASCII numbers and  */
			decimal_digit BYTE,                      /*calls WRITE for each  */
				ascii_digit BYTE;                    /*ASCII digit           */

			ascii_digit = decimal_digit + '0';
			CALL write(@ascii_digit, 1);
		END convert_decimal_digit;

	print_coin: PROCEDURE (text_ptr, value); /*Formats writing of change */
		DECLARE                              /*values and TEXT; calls    */
			text_ptr POINTER,                /*Write_decimal procedure   */
			value WORD,
			text BASED text_ptr STRUCTURE (cnt BYTE, string(1) BYTE),
			text_cnt BYTE;

/*                              NOTE                                         */
/* When you are searching backwards from the current cursor position, the    */
/* cursor is positioned at the beginning of the string when a match is found.*/
/* With the AGAIN command you can repeat the last edit command performed.    */
/* Use it now to search for another match of the string THIS IS A TEST.      */
/* Enter A                                                                   */
/*                                                                           */
/* In our case, this was the only string the editor was able to find.  Let's */
/* use the FIND command to find the start of our last set of editing instruc-*/
/* tions.  Enter F.  Enter the string to search for as shown below:          */
/*     QUIT <ESC>                                                            */
/* NOTE: If the cursor is positioned above the string you are looking for,   */
/* it will stop at that string since a match has been made.  Press A to      */
/* search again.                                                             */
/*                                                                           */
    IF value = 0 THEN
	                RETURN;
		CALL write (@('  '), 2);
		CALL write_decimal(value);
		text_cnt = text.cnt;
		IF value = 1 THEN
			text_cnt = text_cnt - 1;		/* make singular */
		CALL write(@text.string, text_cnt);
		CALL write(@lf_cr, 2);
	END print_coin;

	payment: PROCEDURE;                            /*Specifies order in which*/
		DECLARE                                    /*change information is   */
			s_text (*) BYTE DATA (8, ' dollars'),  /*written; calls          */
			q_text (*) BYTE DATA (9, ' quarters'), /*formatting procedure    */
			n_text (*) BYTE DATA (8, ' nickels'),		
			d_text (*) BYTE DATA (6, ' dimes'),		
			p_text (*) BYTE DATA (8, ' pennies'),		
			p1_text (*) BYTE DATA (7, ' penny');		

		IF (dollars OR quarters OR dimes OR nickels OR pennies) = 0 THEN
			CALL write(@('No change'), 9);
		ELSE
			DO;
				CALL write(@('Change = '),9);
				CALL write (@lf_cr, 2);
				CALL print_coin(@s_text, dollars);
				CALL print_coin(@q_text, quarters);
				CALL print_coin(@d_text, dimes);
				CALL print_coin(@n_text, nickels);
				IF pennies = 1 THEN
					CALL print_coin(@p1_text, pennies);
				ELSE
					CALL print_coin(@p_text, pennies);
			END;
	END payment;

	get_input: PROCEDURE (text_ptr) WORD;   /*Writes request to output;   */
		DECLARE                             /*converts each received ASCII*/
			text_ptr POINTER,               /*byte to a decimal digit and */
			value_ptr POINTER,              /*assembles decimal values    */
			value WORD,
			char BYTE,
			not_done BYTE,
			text BASED text_ptr STRUCTURE (cnt BYTE, string(1) BYTE);

		CALL write(@text.string, text.cnt);
		value = 0;
		not_done = TRUE;
		DO WHILE not_done;
			char = read;
			IF (char >= '0') AND (char <= '9') THEN
				DO;
					value = value + char - '0';
					value = value / 10;
/*                                                                          */
/*                               NOTE                                       */
/* The cursor stops at the end of the string when it finds a perfect match. */ 
/* Let's search backwards for a string now.  Use the -find edit command to  */
/* do this.  Type -.  Now enter the string to search for:                   */
/*    THIS IS A TEST <ESC>                                                  */
/*                                                                          */
          END               
			ELSE
				not_done = FALSE;
		END;
		RETURN value;
	END get_input;

begin:;
	DO;
		CALL write (@lf_cr, 2);
		paid = get_input(@paid_text);
		purchased = get_input(@purchased_text);
		CALL write (@lf_cr, 2);
		change = paid - purchased;
		dollars = change/100;
		coins = change MOD 100;
		quarters = coins/25;
		coins = coins MOD 25;
		dimes = coins/10;
		coins = coins MOD 10;
		nickels = coins/5;
		pennies = coins MOD 5;
		IF paid < purchased THEN
			CALL write(@('NO CHEATING!'), 12);
		ELSE
			CALL payment;
	END;
exit:;
	HALT;
END;
/*                                QUIT                                       */
/* To exit from the I2ICE editor and return to the tutorial use the QUIT     */
/* command.  Enter Q.  Notice the menu options available to you.  You have   */
/* the choice of aborting from the editor (without saving the code), exe-    */
/* cuting the file (I2ICE debug object file), initializing a new edit session*/
/* without exiting from the editor, or writing the code out to a disk file.  */
/*                                                                           */
/* Since we did not make any changes to our source file, we do not need to   */
/* save it.  Let's use the ABORT command to exit from the editor.  Enter A.  */
/* The editor will prompt you with the message: all changes lost? (y or [n]).*/
/* Enter Y.  After the I2ICE prompt (*) appears on the screen, enter N       */
/* <Enter> to obtain the next tutorial screen.                               */